Ublock Origin is an obvious one, but I also can’t stand not having Foxy Gestures anymore. It adds customizable mouse gestures, so you can set it up to have easy swipes to go back a page, reload a page, close a tab, etc, and it feels wonderful and smooth to use compared to just using the traditional buttons to do everything. Honestly it’s kinda wild to me that this isn’t more popular now that people are so used to phone gestures. It’s good for the same reasons!
Firefox (I am not going to repeat the obvious ones that have been mentioned numerous times):
Curious, what are you looking for in the ip info of a site?
I don’t actually care about the IP address, I am just curious if a website is accessed via IPv4 or IPv6.