I got into this situation in chamber 19 where you get stuck in a corner right before entering the pipeline for cubes (0:26 in the video). You can't move/jump out of it. After loading a quicksave or regular save from anywhere in the game, I'm still in crouching position (you auto-crouch in that corner). You can undo the crouch by popping up the menu, but jumping gets you into crouch position again. I haven't actually touched the crouch button during any of this.

Since this is a serious potential run-killer for the blindfolded run (probably 2 hours into the run), I'd like to know if there's any way to get out of this bugged state without having to restart the whole program (= rip run). The real danger is that the entry point of the tube is so close to that buggy corner.

the last time I had trouble with any sort of auto crouch code, pressing crouch once manually fixed it. As for getting stuck there, that's super rare and I don't even know how to recreate it at all.

Pressing crouch manually unfortunately has no effect whatsoever after this bug (not even after loading a quicksave).
Getting into the corner is just a matter of standing on the edge of the gap in the tube, then moving into the direction of the corner. It's not hard to avoid it, but it's a scary thought that rip run is literally one button press away from the route.

while in this state try typing -duck in console. if it doesn't work, reload a save and then type -duck.

That does solve it! Thanks a lot. I'll just have to make -duck a keybind then.