Currently Undoing an update on a note only undoes the last smallest change (like a single keypress in a series of keypresses required to type a word). so typing “hello world” and then pressing undo results in “hello worl”. I think what ankimobile does instead is more ideal where undo note undoes all edits made to that note so that note is now what it was before it even came up for review for that day. What if I am typing in HTML and really mess things up. Currently is nightmare to undo if I can’t remember what I did. Also if you accidentally type another character or something it rewrites undo history and makes it even harder to understand what is happening.
There’s code in Anki to do this already, but it doesn’t currently appear to be working. I’ve logged this on maybe_coalesce_note_undo_entry() is not working · Issue #2974 · ankitects/anki · GitHub