Sure, meaning always depends on context, but this is a lower-level difference. If I copy an English sentence from a hundred-year-old book into Microsoft Word, it doesn't change the meaning of the sentence. If I write a sentence containing emojis on e.g. an Android phone and read that exact bitwise-equivalent text string on an Apple phone
on the same day, it could have a wildly different meaning because of the font. This has already happened -- a few years ago Apple updated their font to have colored foot emojis, which sparked some controversy[1] because the version of the feet for black skin tones (incorrectly) depicted the sole of the foot as black. There was a thread on Twitter (can't find a link, sadly) where someone was confused by the posts talking about this because their Android phone's version of the emoji showed a side view of a foot instead of a bottom view. The original tweet was unintelligible to this reader because they were using a different font than the writer.
One of the advantages of written language is that it's based on a discrete set of symbols that are used to form discrete words. This allows writing to last much longer than many other forms of communication. Emojis are a weird semi-discrete hybrid form of communication, which means they're bound to cause problems as time goes on.
[1] https://www.dailymail.co.uk/femail/article-6347073/People-ou...