The game intermittently, but very regularly goes into a jittering loop when crouch / sneak is selected.
I have just installed the part 2 caves and cliffs update 2.34. Prior to that the game was playijng well with just a couple of issues.
Linked issues
Comments

does this issue still in 1.19.81? as requested, please attach a video for this issue, if the video was to large, you can post it on YouTube then send the link to here
Are you able to attach a video of the issue?