lemonmannutsball In general cellular uses more 'power' than WiFi, so i think this might be expected behavior in that sense. I'm not sure what modem pixel 6 uses, but there are also differences in efficiencies in modems, it could be that for examole the moden in pixel 6 is less effecient than in a pixel 9.
I suppose there's nothing wrong here and normal behavior, though this could be manifested more if the battery is losing capacity aswell, in the sense that u will notice those differences more.