With the Alpha 4 I too had it become very jumpy. I found that if I opted out of the Preview in the OpenXR Dev Tool (so back to 108.2111.23004) it helps make it smooth again. Also, if you are in the OXR preview then it can work better if you start in VR mode before entering the flight.
I’ll try again with the latest beta to see if it still does it.
EDIT: Seems better now, in that I can’t get into the ‘judder’ mode I had with v109 and the alpha’s with no motion reprojection and set 100% OXR (WMR Reverb/ i9 / 3080Ti)