In my third post in this thread I had you go over the Mail Notification Settings for Windows 11 Mail app. They are in Mail Settings (gear icon in Inbox) > Notifications. I also doubled back to them several more times in the thread.
My understanding is that you use the Mail app and also get your mail in the browser, is that correct? If so it appears you are getting Notifications from both places. I've gone over the settings with you for both places.
If I'm misunderstanding anything please clarify.