Avatar shifts to not symmetrical pose in play mode

Hi! I’ve been creating avatars from the scratch for a bit, and recently I paid attention to an avatar shifting posture in play mode, with IK goals going all over the place. Otherwise it retains proper T-pose, both in blender and unity.

This avatar has rotation constraints in the legs but it also happens on another avatar that has none.

I’ve looked everywhere and couldn’t find any solution to the issue, thank you in advance!

Edit: I did made sure all bone rolls of armature bones are set to zero, and applied to FBX in unityproject. Also made sure all bones in unity have symmetrical world transforms, and disabled constraints for sake of troubleshooting.