I have the same issue. Almost. If I go to my Collabora server I get the Apache Default Page.
Also looking (in vain?) for a solution.
Also on Nextcloud 23. Wanted to upgrade from 20 to 23, accidentally the system tried to upgrade the directly which I know it does not do. Had to reinstall NC because I could see no possibility to mend the problem any other way. I have now been able to install NC 23 and it seems to work well.
Collabora does not, though.
Any suggestions from the community?