I think the issue with popular culture in America is that it has stagnated since the early 2000s. Our culture hasn't developed -- at least not in any marked way -- in twenty years.
I play a game with my children when we're driving somewhere (pre-Covid, back when we used to go anywhere); I would play them popular and rock music from various times and see if they can identify when it's from. Every decade is identifiable, by and large -- you know what each decade from the 40s through the 90s sounds like. But then you hit the 2000s until now and everything sounds the same, sometimes recycling old sounds, sometimes just generic. You don't hear anything and say, "oh, this is obviously the mid-2010s." It's the same for most other cultural aspects. Fashion? Literature? Movies? Same, same, same, coupled with recycled material.
Horkheimer and Adorno wrote about the culture industry -- popular culture is that which can be mass produced so everyone can consume it in order to make folks passive so that, in part, they don't question their economic conditions; this focus on the calculation of material interests in the culture industry results in a loss of creativity. So, is it degenerate? I don't know. But it is stale because people have become quite passive with easy access to entertainment (think expansion of the internet and introduction of smart phones). The culture industry, and popular culture by default, just don't have much work to do.