As I opened this post, I already indicated that I had opened an issue on GitHub, the one mentioned in the previous comment.
https://github.com/nextcloud/server/issues/45132#issuecomment-2098151745
Now, whoever applied the fix, which is hoped to be released in the next release, encountered this problem:
"for us #45093 did fix the auto logout error but Nextcloud Office / Collabora Code could not access the files any more, so we had to choose what’s more important, NC Office or a reliable Talk App.
A general question: Does the Maintenance and Release Schedule, in this case for 28.0.6 (2024-05-23) and 29.0.1 (2024-05-23), also apply to critical issues like that or are hotfixes rolled out via the Updater earlier?".
I don’t know if this can also cause problems with OnlyOffice. I believe that must be very careful when performing the update, at least try the operation of the main applications.