When you change your avatar's height (in any way), it causes a flicker (or something like that, I am not sure how to call it) where your viewpoint and avatar is a little bit off for a frame.

While this is not really a big issue if you don't change your size often, when I made a size changing system that transitions your scale over a period of time (with OSC), it caused massive flickering when it's not properly tied to the frame-rate. And even when I did make it tied to the frame-rate, changing the height still caused some flickering (when changing it very slowly) and a weird view. Then I checked a world that had a similar system and it had the same issues under the same conditions.

I only tried this on desktop so far. I'm not sure how much it affects VR.

BTW, I tried a workaround (by adding some noise to each height change so they don't get rounded to the same height 2 frames in a row) but it's neither smooth nor reliable, and still has the same weird view issue.