On Linux Mint 20.3 last night I updated Opera from 101.0.4843.58 to 102.0.4880.16 using the Update Manager. Got the update but in addition to all bookmarks and history being wiped out, Opera thought it was an entirely new installation and wanted me to go through a new installation setup.
The night before I successfully did the same update on another Mint 20.3; everything seemed fine.
A couple hours before the above fiasco I tried to update Opera from the same old version as above on a Win 10 machine but was told Opera was up to date.
I haven’t tried to update Opera on a Mac.
This could have been a one-off event, but backup your bookmarks before updating Opera, make note of your settings, and be aware that even if you do backup bookmarks your history will likely not get backed up along with your bookmarks.