Steps to reproduce.
  1. Prior to testing, make sure the menu is locked.
  2. Put the headset upside down or sideways.
  3. Exit and restart VRChat
  4. Open the main menu .It is permanently sideways until unlocked or restarting VRChat.
  5. Click the lock button in the main menu
  6. Notice the menu is no longer in the wrong orientation.
Three fixes I can think of: (a) Lock the menu to whatever orientation you're in each time you open the menu. (b) Lock the menu to some axis aligned orientation (e.g.to handle lying in bed or standing up, but not in between. (c) Always force the menu to y-up if locked.
Three people have run into this issue recently. I think it's more common than it ssounds.
One friend has encountered it on mobile too, while starting VRChat while lying on bed, but I am not sure if they were using link.
I believe the previous issues were closed incorrectly. The problem has existed for a long time, and it is still a problem. https://feedback.vrchat.com/open-beta/p/1238-crooked-menu