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You might also be interested in vundo: https://elpa.gnu.org/packages/vundo.html . It is a newer alternative that is to my knowledge more robust, but depends on Emacs 28.
Could you elaborate on "more robust"? I use undo tree currently and the readme suggests it has less features- does undo tree have problems that vundo solves? I don't mind undo tree needing to be enabled all the time or replacing undo commands.
In my eyes it is the more idiomatic implementation.