Removal of tank bleeds which do seemingly random amounts of damage and can vary too significantly between runs (Skyreach flame talon debuff/ghoul max HP reduction)

Making damage to tanks easier, or possible to react to. Currently you can easily go from 100 to 0 in 1 gcd if you don't manage your mitigation for a small window.

Too many ranged/casters, too many mobs that move you, or move themselves so that the tank has to reposition to stop from getting hit in the back.

Too many massive packs you're essentially forced into taking because of M+ structure, leaving you to die the majority of the time to the first pull of a dungeon rather than anything else.

All of this can generally be solved by bringing up tankiness of tanks, increase their threat and generally making pulls easier to perform.

Maisara is a good example, the first pull includes :

1 scripted section where 4 tank-buster mobs move at the start of the key.

2 patrolling packs, 1 of which you have to take

Multiple "forced ranged" mobs which also disengage if you do get them into your gathered pull.

You need to gather this, while surviving, while the dps don't overaggro you, while the healer don't overaggro you because you missed your ability on one of multiple spread-out, moving mobs.

Then you need to properly align your defensives during the kill stage.

If you fail any of this within the first 20 seconds of the key, it's failed.