Whoa @JPM13 @Shiro this is indeed terrible, apologies for this. We confirm the files or content have not mixed up, it was a temporary authentication mixup: the server was returning some sessions for another user. The code responsible for this has been removed.
Once we lift the maintenance in the next hour you should see all your files again. Depending on the behaviour of the client it could either synchronize with the last content or keep the old files. Please delete any files or content not belonging to you.
Meanwhile we are assessing the number of users impacted, we haven’t seen this ourselves so we’re uncertain of how many cases there are.