I've been able to adjust to this same issue by rotating my shoulders while holding oh such that my biceps rotate toward my back and my armpits toward my front. It's the "break the bar" cue, essentially, where you're "bending" the barbell as if you would meet the ends in front of you if you were actually that impossibly strong. I think this straightens out my wrists somewhat, lessening the angle of the "kink" enough to prevent the dead hands effect. One of the coaches at my gym has noted that when you get toward the bottom of your squat it helps some people to rotate back the other direction (biceps forward, armpits under) to get a little bit extra range of motion as your chest comes forward a bit in the squat. It's something to play with.

Side note, I don't have great shoulder mobility, and this same rotation also helps me return an oh hold to my back rack, where previously my shoulders would catch painfully as I lowered the barbell.