It might be that, i'm using a laptop with 6gb ram and APU from ~2015 i think. i haven't tried on my Windows PC yet to see how it works.
Aren't 16K textures a bit excessive? Are they atlases?
Could you consider making a low-spec build with max limit of 4k textures (Easily done on unity build settings)
I see, it's alright, you can't really do anything about it since they are atlases or it would be much effort.
I think texture format is something to check if not already but I don't know much about it in unity.
Anyway i'll give it a try next time hopefully or maybe next games.
Thanks for taking time to answer and investigating.
