Pop up ads in the lower right corner of my screen

I am seeing pop up ads like these on the lower right corner of my screen since I updated to windows 11. I've never seen this with windows 10. Microsoft is telling me these are coming through my browser. These are not when I am in a web site and get the pop up to allow notifications, I always say no. These come @ 1 per week or less and I don't seem to be able to stop them. Is there a setting in firefox that will stop them or is this a microsoft issue? thanks brian