Bullseye running hotter than Buster

Folks, this is an initial observation and I have not done any in depth comparisons to verity this but just noticed after installing FA on a bullseye image that it was running a few degrees hotter than I recalled on a buster image.

Now I understand the Pi4s get a faster clock speed but I am running mine on a Zero W

Appreciate ambient temperatures are a little higher but my Bullseye image seems to reach 50c almost immediately whereas my Buster image tended to be mid 40s.

I shall investigate further but curious if anyone else noticed higher running temperatures with Bullseye?

Geoff