I turned Notifications off in Windows following these instructions and no change.
I unchecked ‘Use System Notifications’ as well, no change.
Then try using the builtin Backup and Restore to transfer your exact eM Client complete settings and data from your other Windows 11 pc to your upgraded Windows 11 pc.
See the following post from @Gary on how to transfer your exiting email with all the settings etc to your new computer using the backup and restore feature in eM Client.
[Transfer eM from one pc to another - Frequently Asked Questions - eM Client] https://forum.emclient.com/t/transfer-em-from-one-pc-to-another/58064/9
Or see the eM Client support blog page on how to transfer from one computer to another using either “the builtin backup and restore” or optionally “via the hidden database folder”.
Note:- Before doing any of the above options, make a manual backup via “Menu / Backup” on your upgraded Windows 11 pc incase you need to restore for any reason. You can see when the backup is complete in Show Operations via clicking the dropdown on the right of Refresh.