What is the quality that is so diffirent in seasons 6 an on? Is it just aging?

I am just rewatching and I stopped in the middle of season six, just that vibe that I was binging in 1-4, especially 1-3 is gone. I know this sounds superficial, but every one of the actors changed so much, they were like more ... perfect, skinnier, more spotless version of themselves? More serious?

Like I know they physically aged, but it felt like more than that. That magical whimsy of the first 3 seasons feels gone. But I feel like this is life in general, too - everything is so fun and light before you turn 30?

(I do love all seasons, just this rewatch feels different)

Sorry for the coherence of this, it`s the time of day I should have been sleeping.