We can export it in 4K but it will look blurry. We did an 8K build before and it looked blurry on that.
We'll have a look into other optimization options in the meantime. The 16K textures are atlases and necessary for our workflow.
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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.