Considering QOIs association with gamedev, HDR textures would be decent guess

Not the OP but as an example, the difference between 8-bit and 10-bit on visual complexities like gradients are very noticeable.

I have a pipeline for scanning of analog sources like film. Since these are meant to be edited after scanning, 8-bit range is much to limited.

I render accumulation fractals like the Buddhabrot at 32 bits per channel. So far I have only used about 27 bits but it's nice to have a bit of headroom.

> Out of curiosity, what for?

Modern cameras can usually sense 12-bit colors. It's wasteful to throw this information away. We historically use 8-bit colors because of technical limitations in the past and because it's conveniently matching a byte. But quality-wise, 12-bit color is just much better.