I don't use Firefox often because of the constant updating that prevents me from using it right away. Chrome and Brave don't seem to do that, at least not in the same obvious way that Firefox does.
Ironically though, I wonder if not using Firefox much is the cause of that annoyance. In other words, Firefox usually waits for an opportune time to update, but if it's been closed for a long time, it likely decides that it's too out of date, and updating asap is critical for security.
I'll reiterate my recommendation for ESR, it's Firefox but for people who want less frequent updates. :)
They should be smaller downloads that install more quickly though, shouldn't they?
I'm not on Firefox ESR, but switching to Windows LTSC made Windows updates a lot less painful and less noticeable, even though technically the frequency is the same.
You can use ESR[0] version of firefox the equivalent of LTSB windows. Or use a registry hack[1] to disable updates for regular firefox if you use Windows.
I'll reiterate my recommendation for ESR, it's Firefox but for people who want less frequent updates. :)