Ask HN: Anyone tracking the degradation of LLM's against new domains?

I'm starting to notice that for newer projects that I've been playing around with (most recently react router V7), LLM's are worse due to lack of training data, compared to something like Rails, that was around long before LLM's.

I would imagine this dependency on LLM coding makes people less willing to adopt new technologies, ergo, training data would probably no longer be as plentiful? Doesn't this eventually lead to a long term degradation of LLM's?

Anyone else noticing this?