If you get used to squatting in knee sleeves then you will get used to the feeing of them tightening up as you hit depth, so if you were to then squat without them you would lose one sort of feedback as to depth/technique. That’s really the only form of proprioception that I get from them, other than that they just keep my knees warm and if they are tight enough you will get an additional rebound out of the hole.
If you are not properly warmed up or if your muscles and joints get cold then it will be harder to use good technique. I don’t see the compression as having any significant effect since it’s minor, unless you are talking about an extra tight pair of SBDs of Titan Yellow Jackets. As for keeping the legs stable, you cant expect a 5-7mm thick piece of neoprene to stabilize anything.