Emails going to straight to the delete folder and being marked as read.

We have an open ticket with MS for 7 months now... for one user of our company thas this issue. A second one had same issue but with much less rate of occurence. We now have a second one , the difference between them is that one has random emails moved to deleted as Read and the other one as un-read. All troubleshooting actions performed many times (no rules, user of MFCMAPI to check / delete any garbage ignore records etc., checks to all possible parameters - even Azure App ID checks/checked if user accidentaly got phished having something set up there. 

What appears to gave a solution were below steps :
1) Changing user's password, he has 2FA enabled just fyi 
2) kicked out all sessions
3) Kept laptop closed 
4) Installed email account to new laptop 
5) Test for two weeks now , not a single email moved to deleted folder

The rate of occurense for that old case was having daily and randomly - not a pattern , 3-6 messages to the deleted folder as "unread" .  

Note: In all three cases, users have iphones 

Via Exchange Messare trace-> Message trace search -> by searching via Message ID you get as result "The message was delivered to the recipient's mailbox. Because of an inbox rule the recipient set up, the message was delviered to the following folder: Deleted Items

Whereas via  Purview searching  via keywoards - criteria mixes things up not resulting to results confirming the fidnings of previous exchange message trace.