Mahomes has the full dead weight going limp thing perfected when he gets touched out of bounds. Allen has a more theatrical throwing of his body to the ground in his flops.
Likely was not coming back to Lamar. He was running down the field, and after the ball was thrown he stopped to run back towards the LOS because the pass was such a lobbed underthrow. Honestly seemed like one of those passes intended to draw PI.
I think there is this psychological thing where refs give great teams more leeway and the benefit of the doubt. I see it in other sports like hockey too.
I haven't seen Lamar go through his progression and throw downfield yet. I think Allen has an advantage there even if we do more of a dink and dunk approach.