Firefox doesn't send or give popups notification beyond the notifications for updated version of Firefox. If those only show up when your on YouTube and no other sites then that is coming from YouTube and if the account is a YouTube account then they are sending tracking based on that account activities. Since there is no screenshot of the popups no can know what is happening.

I keep receiving notifications I've already dealt with, specifically from Youtube, as of writing this is the third day I've had to deal with them. The notifications pop up inconsistently, anywhere from 5 minutes to an hour, but when they do pop up, it's a barrage of every notification I've already read since it began. This may be an issue with Youtube itself or Windows, I don't know.

Are these little popups on bottom right corner?. If so then they may be web push notifications from sites you have allowed to send you notifications. You can revoke these sites.

https://support.mozilla.org/en-US/kb/push-notifications-firefox https://support.mozilla.org/en-US/kb/push-notifications-firefox#w_how-do-i-revoke-web-push-permissions-for-a-specific-site

They are push notifications, yes, I still want to receive them, just only ones that are new.

I have this problem also. I have Windows 11 and have all the updates installed and am using the latest Firefox version. This just began a day or so ago. I have tried restarting the machine, clearing the cache, turning off the notifications, but nothing is working to clear up this problem. The backlog of notifications which are getting pushed all day long is getting bigger. Something in the last few days is causing this and its not something we users have done.

Same problem here. The notifications are coming from Yahoo! web mail https://mail.yahoo.com. I want to be notified when I get a new email, but I am getting repeated notifications for the same emails, even if they were previously read or even in the trash. When I get a new email, I get notified of it and then a barrage of previously read emails. I could just turn off email push notifications in Yahoo! mail, but it would turn off notifications for new email too, which something I would like to keep.

Update: I turned off push notifications in Yahoo! web mail, then waited overnight and turned them on again. After that the issue with repeat notifications in Windows 11 was gone.

I tried Brian402's solution, however that did not clear up my Youtube notification problems. Nor did updating to the latest Firefox 132.0. I am at my wit's end with the notifications. I can get them to stop for approximately a half hour by clearing my cache but then they begin again once a new notification comes through. Really annoying and frustrating!

Been having the same issue on windows 11. I want notifications, from "gameflip.com" yet I am getting like a weeks worth of them sent all at once, repeating a few times a day. I don't have notifications for other websites turned on so I can't tell you it's a website push issue or Firefox repeating the messages or windows being weird. My windows 10 PC is not having this issue. I have current main OS and Web updates, no beta releases.