Edit: A user found the issue and clarified its an issue with the website using placeholder pointing to localhost, probably when developing. This old post title has been changed from "An accounts profile causes a localhost Port Scan on Firefox" to "A website causes a localhost Port Scan on Firefox" to reflect the new found information. Solution here (a reply in this post): https://lemmy.ml/post/51842257/27445377

Post in question: https://lemmy.ml/post/51833596 which links to the actual "problematic" webpage: https://radicle.dev/guides/user

A ~~users account / profile~~ post causes a localhost Port Scan (attempt) on my Firefox, when I either open the page or even when posts of the account are listed in my Subscribed feed view. I just noticed this because I have an addon installed that blocks and notifies me about this: https://addons.mozilla.org/en-US/firefox/addon/port-authority/ The addon lists port 3000.

Is this something to be concerned about?

Edit: Removed the link from this Post URL, so it does not cause the Port Scan to others I was reporting here.