How do you actually know if youve outgrown your bike or just gotten bored?

Been riding a Ninja 400 for about two years now. Daily commuter, weekend mountain runs, a few longer trips. The bike does everything I ask of it. I'm not dragging knee or pretending to be a racer. But lately I catch myself scrolling marketplace looking at MT-07s or even a used Street Triple.

Part of me thinks I just want something that sounds meaner and has more punch out of corners. The other part worries I'm confusing boredom with skill progression. Like maybe a bigger bike just masks mediocre riding instead of actually making me better.

For people who moved up from a small bike, how did you know it was time? Did you hit a clear limit with the bike or did you just want a new experience? Anyone go back down after upsizing and realize the small bike was fine all along?

Not trying to be the fastest. Just trying to figure out if the itch is legit or just new bike fever.