I encountered this problems when putting banners up. i found the easy way to fix it was not to put the banner against the wall and rather put a solid block in the wall or a subtract in the wall. it only bugged out like that previously tho when i was far away
but making signs outa solid full blocks seemed to work ::shrugs::
mmmm z-buffer fighting.. does changing renderer fix it?... and doesn't usestencil have something to do w/ these problems? :-/ thot i read something similar about this b4 that had a solution involving turning that on.