rekker

One observation to contribute that I haven't noticed elsewhere.  On PS4 Pro.  I've got a normal long-term world, lots of animals, entities, redstone, etc.  Upgraded to 1.18 and now running latest (2.35 iirc).  I have not taken any actions (like those mentioned previously here) to reduce lag and I have all the symptoms everyone has listed.  Here's what I've noticed under several situations.  When I pound the crouch button a few times, the player reacts/crouches normally but then after I stop pressing anything, he'll kind of vibrate up and down very briefly then it seems the lag will clear.  One situation where this seems most consistent is when I get into the mode where attacking isn't doing anything - like swinging at mobs that aren't really there.  I'll hit the crouch button a few times and more often than not, the issue clears itself and the next attack actually hits.  The other scenarios where I've seen the crouch trick help some (but not as consistently as with the ghost mobs) is: waiting on a block I've broken to either actually break or magically reappear and waiting on a button or pressure place to actually respond to my input.

I can confirm this on the PS4 - same behavior/symptoms.  It started after installing the PS4 1.16.210 update on 3/9/21.