In my view, the Voynich manuscript is a book of variations.
On a larger scale, we can observe the evolution from Currier A to Currier B. Word types containing the sequence [ed] become increasingly frequent, such that as <chedy> is used more often, similar words like <shedy> or <qokeedy> also rise in frequency. Simultaneously, words with the prefix <qok-> become more common, while words typical of Currier A, such as <chol> and <chor>, gradually disappear. Moreover, dramatic differences can be observed even within the same quire. For example, the glyph EVA-[m] is absent on some folios in Quire 1 but frequently used on others, as seen in the bifolio f2/f7 versus f3/f6. (see You are not allowed to view links. Register or Login to view.).
At the word level, for each common word type, there are typically multiple variations differing by only a single quill stroke. For instance, along with the word [daiin], the text also contains [dain] and [daiiin]. However, less common alterations also occur, such as changing an [i] to [r] or an [e] to [s]. For example, in addition to [daiiin], there are two instances of [dairin] (see You are not allowed to view links. Register or Login to view.). Similarly, alongside [chedy], a few instances of [chsdy] can be found (see You are not allowed to view links. Register or Login to view.).
At the glyph level, it's possible to observe multiple variations. For instance, there are two variants of the [s] glyph. The first variant consists of two quill strokes, suggesting that an [e] was altered into an [s]. A notable example of this variant is the unique glyph group [qoesedy] in line <f82r.P2.24>. (For reference, the corresponding variation [qoeeedy] appears three times in the text.) Typically, an additional quill stroke is used to change [e] into [s] or [ch] into [sh]. However, this technique isn't limited to these transformations. In some cases, the plume is also added to other glyphs, as seen with [qoky] and [saiin] in line <f2r.P.10> (see You are not allowed to view links. Register or Login to view.).
In lines <f10r.P.9-12>, the sequences begin with [oy], [oq], [ro], and [ro] (as seen in You are not allowed to view links. Register or Login to view.). However, the shape of the [r] in these two instances is highly unusual. (Note: Additionally, the sequence [oq] is also rare in the Voynich text. There are only 20 tokens starting with [oq]).
Irregular variants also exist for gallow glyphs. For example, the word type [chcthedy] is generally written as expected six times, but on page <f115v>, it appears with an additional quill stroke connecting [ch] to [k] (see You are not allowed to view links. Register or Login to view.). Another example of an ambiguous glyph is the [p] in [pchol] in line <f14r.P.8>, where it's unclear whether this glyph represents [p], [k], or an entirely new character (see You are not allowed to view links. Register or Login to view.).
What does this mean?
Given that the Voynich manuscript employs an unknown writing system, and that variations appear to play a significant role within it, it is exceptionally difficult to determine the reasons behind the variations we observe in glyphs like EVA-[k] and EVA-[n].
One possibility is that the handwriting of a single scribe evolved alongside the "generating algorithm" of the text. To my untrained eyes, the writing in Currier A appears more broadly spaced and seems to have been written more slowly and carefully, whereas the writing in Currier B appears more compact and fluent. This could suggest that the scribe became more experienced with the new writing system over time. Another possibility is, of course, that these variations are the result of two different scribes working on the manuscript. However, I find this explanation less likely due to the numerous similarities in the script, particularly in the case of EVA-[k]: "For nearly every page it is possible to find instances of <k> written with bowed and with horizontal crossbar, respectively. Additionally, on nearly each page some instances of <k> show an overlap between vertical stroke and crossbar, also indicating two strokes." (see You are not allowed to view links. Register or Login to view.)
It's also important to consider that we analyze magnified images of the manuscript. Since it is a handwritten object, some degree of variation is expected. However, I wouldn't rule out the possibility that the scribe intentionally wrote certain glyphs differently for unknown reasons. (We cannot even be certain whether what we transcribe as a single glyph was, in the eyes of the scribe, actually one or two distinct glyphs. Nick Pelling is even suggesting that the length of the flourishes for EVA-[n] transports some meaning: You are not allowed to view links. Register or Login to view.).
On a larger scale, we can observe the evolution from Currier A to Currier B. Word types containing the sequence [ed] become increasingly frequent, such that as <chedy> is used more often, similar words like <shedy> or <qokeedy> also rise in frequency. Simultaneously, words with the prefix <qok-> become more common, while words typical of Currier A, such as <chol> and <chor>, gradually disappear. Moreover, dramatic differences can be observed even within the same quire. For example, the glyph EVA-[m] is absent on some folios in Quire 1 but frequently used on others, as seen in the bifolio f2/f7 versus f3/f6. (see You are not allowed to view links. Register or Login to view.).
At the word level, for each common word type, there are typically multiple variations differing by only a single quill stroke. For instance, along with the word [daiin], the text also contains [dain] and [daiiin]. However, less common alterations also occur, such as changing an [i] to [r] or an [e] to [s]. For example, in addition to [daiiin], there are two instances of [dairin] (see You are not allowed to view links. Register or Login to view.). Similarly, alongside [chedy], a few instances of [chsdy] can be found (see You are not allowed to view links. Register or Login to view.).
At the glyph level, it's possible to observe multiple variations. For instance, there are two variants of the [s] glyph. The first variant consists of two quill strokes, suggesting that an [e] was altered into an [s]. A notable example of this variant is the unique glyph group [qoesedy] in line <f82r.P2.24>. (For reference, the corresponding variation [qoeeedy] appears three times in the text.) Typically, an additional quill stroke is used to change [e] into [s] or [ch] into [sh]. However, this technique isn't limited to these transformations. In some cases, the plume is also added to other glyphs, as seen with [qoky] and [saiin] in line <f2r.P.10> (see You are not allowed to view links. Register or Login to view.).
In lines <f10r.P.9-12>, the sequences begin with [oy], [oq], [ro], and [ro] (as seen in You are not allowed to view links. Register or Login to view.). However, the shape of the [r] in these two instances is highly unusual. (Note: Additionally, the sequence [oq] is also rare in the Voynich text. There are only 20 tokens starting with [oq]).
Irregular variants also exist for gallow glyphs. For example, the word type [chcthedy] is generally written as expected six times, but on page <f115v>, it appears with an additional quill stroke connecting [ch] to [k] (see You are not allowed to view links. Register or Login to view.). Another example of an ambiguous glyph is the [p] in [pchol] in line <f14r.P.8>, where it's unclear whether this glyph represents [p], [k], or an entirely new character (see You are not allowed to view links. Register or Login to view.).
What does this mean?
Given that the Voynich manuscript employs an unknown writing system, and that variations appear to play a significant role within it, it is exceptionally difficult to determine the reasons behind the variations we observe in glyphs like EVA-[k] and EVA-[n].
One possibility is that the handwriting of a single scribe evolved alongside the "generating algorithm" of the text. To my untrained eyes, the writing in Currier A appears more broadly spaced and seems to have been written more slowly and carefully, whereas the writing in Currier B appears more compact and fluent. This could suggest that the scribe became more experienced with the new writing system over time. Another possibility is, of course, that these variations are the result of two different scribes working on the manuscript. However, I find this explanation less likely due to the numerous similarities in the script, particularly in the case of EVA-[k]: "For nearly every page it is possible to find instances of <k> written with bowed and with horizontal crossbar, respectively. Additionally, on nearly each page some instances of <k> show an overlap between vertical stroke and crossbar, also indicating two strokes." (see You are not allowed to view links. Register or Login to view.)
It's also important to consider that we analyze magnified images of the manuscript. Since it is a handwritten object, some degree of variation is expected. However, I wouldn't rule out the possibility that the scribe intentionally wrote certain glyphs differently for unknown reasons. (We cannot even be certain whether what we transcribe as a single glyph was, in the eyes of the scribe, actually one or two distinct glyphs. Nick Pelling is even suggesting that the length of the flourishes for EVA-[n] transports some meaning: You are not allowed to view links. Register or Login to view.).