Summary: It is very obvious that, in order to reduce the strain on the GPU, banners are made to be static, flat texture when looking from afar, with cloth physics being added as you zoom in or move closer. While I can't say for field battles (which probably means it works alright in that context), in sieges it's the opposite way: static upclose and (seemingly) fully rendered and integrated when afar.
Also goddamn the siege pathing is wonky, please check that thing again
How to Reproduce: Play a siege
The banner on the ram looks fine...
... until it suddenly doesn't
Also goddamn the siege pathing is wonky, please check that thing again
How to Reproduce: Play a siege

The banner on the ram looks fine...

... until it suddenly doesn't