I based my explanation based on your rather sparse description of your situation, since nowhere you said you don't use AI and nowhere you included any details about your airport so, my explanation didn't "make sense", because you haven't included anything to help me doing a better one.
It's also not very clear if "I'm used to invisible bags depending on viewing angle and distance but not even seeing the carts" really means that ALSO the carts are affected by the viewing angle.
Again, a more precise report might have helped but, of course, nobody ever reported baggage *CARTS* disappearing by viewing angles before, while almost everybody that reported disappearing vehicles like that, always used AI injection and/or very dense airports, that's why I started with the most common explanation, lacking any better details from your report.
So, assuming you really mean the carts are also disappearing depending on the viewing angle, then you are the first one ever reporting this so, at this time, we have no idea what might causing it, and are waiting for further reports.