I'm confused...am I running DDG's browser, or simply the DDG search extension? I know DDG has a browser, but their exhaustive description of protections says that those are all implemented for other brpwsers...so if Firefox is protected by DDG, why should I consider a DDG browser?

I always install DDG in my browser, rather than just using it 'in browser'. A reviewer on YT showed how merely searching with DDG in browser leaves location traces, to anyone who's looking.
He then installed this addon, did the same search, and the location details were gone.
He was using some location software, don't remember which sorry, but he certainly made a clear point.

There is a need for improvement in stability.

Let's face it: the search results are not as accurate as Google.

Seems like ddg sends data to microsoft.
https://cyberguy.com/privacy/duckduckgo-privacy-browser-caught-sending-tracking-data-to-microsoft/
there is also a report by Rebel News.

Not exactly sure why this happened but running this addon caused youtube in non private windows to run really slowly to the point where I could only watch videos at 360p and as soon as I turned it off it went back to normal

Extension parfaite (tout petit bémol : empêche RMC BFM en direct de fonctionner)

Most of what used to be in this addon is already implemented into firefox now, though is easy to set up and oss if you'd like to use it.

Es el navegador que necesitaba privado y muy tranquilo.

Excelente experiencia, Gracias!