Firefox was once very customizable but the Devs decided to close it up, limiting Addons a lot.
Also they decided to integrate features like PDF Viewer, WebRTC, Pocket, Sync, which could have been addons but now increase the attack surface and memory fingerprint of the browser.
Anyways, talking about good use of Addons: Firefox Desktop actually has lots of good Addons really making sense. But it seems Firefox recommends the wrong ones very often
Flagfox: Said to be very privacy invasive, but Alternatives like "Country Flags and IP whois" are better and OpenSource. Meanwhile "Flagfox" is very high up in results
Google Translate: This Addon is the only one that should be recommended. It is opensource and only sends data to Google if the user chooses to. Firefox Translations of course is a good Alternative in the future. But all these recommended Google Translate addons are possibly a privacy threat!
"Weather extension" ? This is not opensource and completely relies on an external service. It is actually very shady
Giphy really? Signal implements a privacy respecting use of Giphy, but an official browser addon will not be privacy friendly. Why recommend it?
Ghostery still recommended, not privacy friendly. At least 3 other blockers were recommended before though
I dont care about Cookies : this is a hard one. In the EU if you dont accept, they get rejected, but outside this doesnt apply! So this addon is harming privacy