Yeah, although a bunch of work on Monero is still a result of work from people that worked on Bitcoin.

There's some independent research there but AFAIK Bitcoin people did not stop working on confidential transactions or fungiblity.

Just explaining that the core tenet was not lost, but that it was still not researched. Bitcoin jump started a research movement that reaped all kinds of cryptocurrency variants as time went on.

https://electroneropulse.org/public/doc/Bulletproof%20RingCT...

Here's a paper whose coauthors belong to the Bitcoin team discussing efficient confidential transactions that were eventually implemented in Monero (not by the Bitcoin team).