Hi Christophe,
welcome to Nethserver Community.
Great, you found a bug - I changed the category and moved the posts to a new thread.
nethserver-collabora uses rh-php71 without requiring it. This was no problem because Nextcloud required rh-php71. Now Nextcloud uses rh-php72 so on newer systems nethserver-collabora doesn’t work anymore.
As a workaround please install rh-php71 and do a
signal-event nethserver-collabora-update
on command line.
I am going to open a bug/PR the next days…