Check the attached photo. It shows a number of objects all with alpha blending enabled (various settings). At extreme angles we get flickering.
I have tried disabling Depth Write as suggested in this thread with no success (instead of flickering, at extremes angles the whole object wasn’t rendered).
So problem here is that your big box behind has blending on it, so it enables depth sorting for it. As avatars have sorting as well - they will both compete in order of drawing.
Order is defined by z-value from camera frustum of AABB of an entity.
So if you rotate camera, centre of box will be closer to camera near plane than z value of an avatar. That will lead to different rendering order.
Ways to go around - if you don’t really need a blending on box, disable it. Then it will be solid.
If you do need blending, then consider splitting it into smaller boxes, so that X and Y would be on same axes as avatars, that way it wont flicker on extreme angles.