Undoing ctrl+shift+backspace doesn't work properly when you've deleted multiple paragraphs across lines
Take any email in the composer and hit ctrl+shift+backspace to delete "everything to the beginning of the line" (effectively deleting the whole paragraph if your cursor was at the end of it) and hit that a couple times, to delete also the lines/paragraphs above... and then try to undo. The result is that some stuff will not be reinserted, and the stuff that does get reinserted gets put in the wrong place.
This problem is also exacerbated if there is quoting or signatures involved in what you're touching. For an easy test case, take any of the evolution gitlab comment notification emails and try to ctrl+shift+backspace into a couple of the quoted contents and then to undo what you've done...
P.s.: this was tested with Evolution 3.32.4