Alas there always seem to be issues introduced by an update. We have suggested better testing procedures and even offered help with (beta- ) testing. I would guess that the updates for the 365 version are also being tested by the users, who update and use.
If I have important work to finish, I postpone the updating until that work is done. It is usually better to wait a few days and see what happens in this forum.
Fact, I guess, is that the software will work for most of the users. For the users that have issue with their system, with an usual (system) setup. The most recent PD update (21.5.3001.0) works for me.
What I always do before updating any of the Cyberlink software is:

• Make a full copy of the program directory of the program involved
• Make a full backup of the folders in the c:\users|%userid%\documents\cyberlink
• Create a system restore point (CyberLink update should that, but just in case…
• (some argue that the above is not enough and that a full system backup should be made, hence a full system restore is required to reinstate the previous version).

Of course this all would not be necessary if Cyberlink would provide a link to the previous version, just to enable their respected customers to continue working…
(Today there was a new version of the Cyberlink Application Manager….)
Hope this helps.

Thank you very much Warry.
Could you tell me please how to create a system restore point or a full system backup?

Restore point: that is simple, search internet for "how can i make a restore point", and you will find many,
try this: https://www.makeuseof.com/windows-11-create-restore-point/

The same for full backups of your system, I would argue that this may be a little bit more tricky because to be sure that your backup will really work when you need it, is.... testing it, which is indeed not something you would like to do.
Try to read this, there are a number of options mentioned: https://www.acronis.com/en-eu/blog/posts/windows-11-backup/
there are also a number of good free backup software packages including from the company mentioned.

A furthermore i would say, unless it drives your business, making a restore point and saving all your PD custom files should be sufficient. In most cases PD will just work.
Have fun.

Thank you very much Warry for your detailed reply