deleted emails returning in yahoo after the move. cannot delete old emails or old folders after migration

I migrated to yahoo last week with all 4 of my comcast email addresses.  emails and folders i delete in yahoo are returning.  to be clear only emails that migrated from comcast to yahoo are repopulating.  emails and folders received or created since the migration are staying deleted.  only the stuff that migrated over keeps returning after deleting them.  (i tried to be sneaky and move them to archive but they still come back to the original inbox or folder and i end up with multiple copies of stuff im trying to delete!)  also i had a fairly large folder of old emails from 2014 to 2020 and i cant delete any of them or the folder.  On yahoo site it said that the folder could not be deleted until the emails were deleted.. so i deleted around 12,000 emails and the folder was empty.  deleted the folder and a day later the folder and all the emails came back.   

trouble shooting steps i tried.... I disconnected my email accounts from IOS (iphone mail app) and i disconnected my email accounts from Outlook (both the ipnone app and also the desktop app)  then i deleted the yahoo app from my phone.  I went to the yahoo account settings page for each email and i closed all open sessions in my web browsers and also they had an option to disconnect access from IOS and also Outlook so there was no third party access.  everything was disconnected.  all my browsers cache and cookies and data were deleted (chrome, Edge, Safari)  I also followed suggestions to disable conversation view in email apps and also tried changing my password and logging in again.   I was ONLY connected to my new yahoo account on the website and I deleted the emails and folders again.  an hour later they started coming back.  eventually overnight the folders were filling up with returning email.  I cant figure out where they are coming from.  they cant be syncing with other apps because they are all now disconnected and it cant be a sync issue between phone and web because the yahoo phone app was also deleted and data erased.  Because it is only happening to email and folders that were migrated from comcast to yahoo is it resyncing with comcast after i delete it?  Is there something in the data that is migrated that is not allowing it to be removed from the yahoo server or is it still connecting to comcast servers a few days after i moved and repopulating the emails and folders?