I have tested this with 188.8.131.52+ (Build ID: a560ee1625393faf5cd5e04c356a9101b701542)
When deleting the contents of a cell by pressing the key "Del" on the keyboard, the conditional formatting for that cell is also deleted. I don't think this is meant to happen because the UI doesn't reflect this change: the cell keeps its color. Also, when pressing "Undo", the contents of the cell are restored but the conditional formatting is not. This can be verified by checking the region in Format -> Conditional Format -> Manage...
You can use the test sheet from #59843. Strangely enough, on that sheet you have to select two cells and press delete, otherwise the format stays correct.
Cannot reproduce on 4.1 master. You marked RC3 as the version that you tested against but then you put
184.108.40.206 which is RC1, have you tested against RC2 and RC3 as well?
Also, you didn't say what operating system you're running.
Version 220.127.116.11.alpha0+ (Build ID: 027bb41aa16793e88e9fc1b3550c8c893363647)
on Bodhi Linux
Marking as WFM as my version is newer. If you have tested this on RC3 as well, please reopen the bug. If the oldest release that you have tested on is RC1 and you have also tested on RC3, please change the version to 18.104.22.168 rc, as Version is supposed to be the oldest version that you have seen the problem, not the latest it has been tested.
I think you are confusing version numbers. 22.214.171.124 is rc3 and 126.96.36.199.alpha+ is master. However, I have been using 188.8.131.52 (!), which is not available in the Bugzilla dropdown - that is why I added it in the comment. This version is supposedly later than rc3.
But I have now also installed and tested with Version 184.108.40.206 (Build ID: 7545bee9c2a0782548772a21bc84a9dcc583b89). Indeed, this version is older than my 220.127.116.11, because not only can I reproduce this bug, #59843 is also still in it.
Sorry that I overlooked the operating system, I added it now and reopened the bug.
Created attachment 74297 [details]
spreadsheet used for test
I reproduce, use the attached file and follow the instructions in the sheet.
Note that according to the document used, it is not always necessary to clear the whole area, sometimes a few cells are enough.
Version 18.104.22.168 (Build ID: 7545bee9c2a0782548772a21bc84a9dcc583b89) - Vista
and also with Version 22.214.171.124 (Build ID: 5b93205) - Vista
It works fine with 126.96.36.199
It might perhaps be good to change the version of the bug?
(In reply to comment #3)
Sorry, I reversed the colors for point 2, please read:
2) initial checks :
1 is in A1 :
A3:C7 - > background red ok
enter 0 in cell A1
A3:C7 - > background yellow ok
*** This bug has been marked as a duplicate of bug 57661 ***