SOLVED 2023-04-05: I discovered that the Comment could not be edited because I had frozen the row where it was located, a long time ago. Editing worked fine some months ago, even though the row was frozen. But now I can edit if I unfreeze the row where the comment is located. Someone must have changed the functionality of Comments, or of Freezing, in Calc/Spreadsheet.
Since the last month or so I cannot edit my comments in Calc/Spreadsheet. The cursor does not work for editing, it only highlights text. See the attachment.
Version: 7.3.7.2 / LibreOffice Community
Build ID: 30(Build:2)
CPU threads: 4; OS: Linux 5.15; UI render: default; VCL: gtk3
Locale: da-DK (en_US.UTF-8); UI: en-US
Ubuntu package version: 1:7.3.7-0ubuntu0.22.04.2
Calc: threaded