First of all, I know other browsers keep update in about page, however, this is why I don’t use them. It wasn’t used to be in a burger menu tho.
Second, add-ons and theme isn’t saying exactly “extensions”. Also, it would take you to the last tab which is by default plug-ins. try it.
I like Firefox and I’d support the developers but they should stick to their roots to keep their current user base.
Every other update would show an ad to use it. Also, you cannot remove it afaik.