Does it get added right at startup, or after visiting a particular site? I suppose even if it is embedded in some other site, if your cookie block is set correctly, the cookie shouldn't be saved.

No, it's not in the startup list. Ran regedit, not in the registry. I'll take screenshots of cookies later, and first boot in the morning, it seems to show up then, that tells me it could be a script but all checks come up negative, more to come tomorrow.

Well here we go, I went ahead and refreshed Firefox, the cookie went away and hasn't come back yet.

I thought after refreshing Firefox I was good to go, unfortunately the bsky.app as shown in the attached is back. I'm at wits end with this, only visited the site once a few weeks ago after reading this article: https://crooksandliars.com/2024/11/why-conservatives-are-so-mad-about-bluesky

Visited the site once to see what it was about, cleared cookie and browsing history immediately afterwards and the bsky.app cookie has continually shown up on my computer, mostly every day, but after a refresh this time it's been five days since I last saw it, does anybody have any ideas on why this is continuing to occur? Thanks in advance, thought I had taken care of the problem.

Could you check whether you have a persistent background process for Bluesky notifications: type or paste about:serviceworkers in the address bar and press Enter to load the page. You can Unregister any process you don't need for current tabs or background notification monitoring.

Anything there? (I didn't find one myself, but it's worth checking.)