Here is how to get rid of popup notfications.
Remember these were allowed by you (or the student) on their computer.
1. Go to your browser settings.
2. Click on Privacy and Security
3. Click on Site Settings
4. Click on Notifications
5. Scroll down to the "Allowed to send notifications" section.
Remove anything under there that doesn't look familiar. Removing them all will not hurt anything so maybe just deleting everything is fine.
You can see that I allow notifications from Google Meet and Microsoft Teams and nothing else.
This should remove any annoying notifications popups from your computer