Tried pretty much anything I could think of. It’s not mips, lods, alpha clip, gpu mem or screen percentage. As far as I can tell it happens with a certain threshold of instances being crossed but that’s dependent on camera distance and also seems related to size (and possible clustersize?) of said instance. Overdraw bug out of parts of the rendering pipeline?
First time I encountered it was with tons of grass on screen so naturally figured ‘Ah right, too dense, lets put a bit of effort into fixing that’ but second time it happened with trees just losing their foliage whilst trunks/barks/branches and foliage shadows still being rendered and it wasn’t like there were thousands on screen. In fact maybe just 200, all properly optimized for real-time.