There is an annoying bug when clicking on a Youtube video from Startpage. It opens a blank tab instead of redirecting to Invidious or Youtube.

The concept is amazing, but the extension fell behind libredirect in basically all aspects.
No real need to stick with it.

https://addons.mozilla.org/it/firefox/addon/libredirect/

My findings are mixed. The add-on works as advertised, but the third party services it uses often don't. Bibliogram usage is now limited to begin with - as detailed in the "Future of Bibliogram" blog post - even on instances where it works. Nitter instance availability is also spotty, I had around 10-30% success rate. Unfortunately this all is not the author's fault, but it's what makes their add-on experience bad.

3 star because not recommended by Mozilla, but more importantly because I constantly hit dead frontends.

While is an all-around good extension. The invidious is broken. It does not proxy googlevideos all the way. Invidition did so until no connection to Google is made on this add-on I can't recommend.