Ctrl+Z is buggy for me too.
(Version 2.1.53 (96bacf79)
Python 3.9.7 Qt 6.3.0 PyQt 6.3.0
Windows 10
All addons disabled)
I encountered the following problems:
it often does not undo the last action only, but also a few of the previous ones
it has no effect on text formatting; e.g. if I use Ctrl+U to underline some text I cannot undo it with Ctrl+Z
on a similar note: let’s say I write three words in the order Word1, Word2, Word3. I use Ctrl+U to underline Word2. Then I use Ctrl+Z and keep it pressed. In theory everything should be undone until the field is empty again. Instead, Word1 and Word3 eventually get deleted, while Word2 and its formatting are not.
most often, if I edit a field and then move the focus to another one, when I go back to the first field I cannot use Ctrl+Z to undo the edit