A Microsoft file hosting and synchronization service.
Contact with Microsoft support
For what it's worth, today I received an update by mail from the 'Microsoft 365 Senior Ambassador' at Microsoft Support I had been in contact with (translated from Dutch to English using Google Translate):
"I have an update regarding your request. This has been picked up by third line and I am now awaiting their analysis. As soon as I receive a message from them, I will get back to you."
After I send a reply to report the issue seems fixed for now, I received the following message from support (again, translated):
"It is not known to me yet that it has been "fixed" with the big sur update. I suggest that we wait for a message from the escalation engineer for additional insights. In the meantime, it can then be seen whether the problem repeats or not."
I have received a final update by mail from Microsoft Support (again, translated through Google Translate):
"I have received a message and it is indeed known that the update should fix the problem."
I hope everyone is experiencing the same with the new Big Sur update!
Erik