May 17 2021
following up my other change i had to make
Set Retention Policy from 1 year to 6 months - what will happen - Microsoft Tech Community
i had a look afterwards to check if there is any negative impact.
Then i saw about 100s of OneDrives got deleted even before my change. They all seemed to be empty and the users were deleted a longer time ago.
It does not seem like a documented behaviour. Many of the deletions happened on one day but after that they seem to continue.
The users were NOT in the range of the deletion date. Anyone else can see this behaviour?