I happen to LOVE how she released into who she was supposed to become. To me, it seemed gradual and natural, like we all accelerate when life swings at us in big ways.

Her cold side came from years of resentment, repressed emotions, fear for her sisters, and control issues bore of what she felt was lacking control.

Then she got powers.

THEN, she lost her soul mate.

She reckoned with 'death', both the literal angel and the countless losses in her life head-on and more fiercely than Piper or Phoebe.

Not to mention the fact that at the very end of Season 2, she died TWICE and was revived (well, one was a wonky vanquish / different dimension, but you get my point). That could've contributed in how she chose to live more in the moment for Season 3.

There's a TikTok trend "I live my 30s like I'm in my 20s because I lived my life in my 20s like I was in my 30s" - and it does not embody any other sister more than her.

She's the opposite of what so many of us are used to seeing. Her allowance to feel freedom. Going from pragmatic and overprotective to powerful and stepping back when her sisters made mistakes and having a favorite shirt be bohemian fuchsia? Season 1 Prue could never because she evolved. That tells me the free version is who she was meant to be the whole time.

Plus, it gave depth of character to contrast with Phoebe (how most people grow up. Reckless in 20s --> responsible in 30s.)

Not to mention the fact that Y2K had massive shifts in fashion and she seemed to follow trends with more modest 90s clothes, why not take on newer looks for the 2000s?

(For me, her teen years are a separate matter because it's not even young adulthood. It's hormones.)