ok more testing. version 0.4.5 (Resolution doesn't seem to matter) At low/720p the game consumes 5.3GB vram. At high/720p 6.3GB, Just by standing around. Walking around the ship it steadily increases until it reaches 6.9GB and then the game crashes with "out of memory" error.
So it has either something to do with lack of streaming, lack of garbage collection, a game bug, KiritoMod doing some extra work, or the game was just plainly made for 16GB gpus with minimal effort spent, which in 2022 is not very surprising to be fair. Although i don't think so, looks like some streaming issue.