also one last thing for aizen not having anti feats
nanana could perceive aizens reiatsu, yes ik he was sealed but same aizen just moments ago was implied to be
above deicide aizen
(also it is said by nanana there are
holes in his reiatsu so he couldve sensed just what was leaking which you can argue shouldnt be much debunking this)
again I aint saying this 100% is a retcon because transcendence was clearly still a thing in tybw
scan 1 scan 2
to explain my interpretation on this
zaraki is transcendental-> zaraki wasnt suppressing which is why fodder couldnt sense him -> kenpachi starts suppressing when he faces gremmy as thats what he does when he starts fighting people to enjoy the fight more -> the fodder shinigami start sensing him