Saturation and hue have no effect when displaying image files

Important Information

mpv 0.33.0-183-gdbbf4a415d Copyright © 2000-2020 mpv/MPlayer/mplayer2 projects
 built on Sat Jun 12 12:21:34 CEST 2021
FFmpeg library versions:
   libavutil       56.70.100
   libavcodec      58.134.100
   libavformat     58.76.100
   libswscale      5.9.100
   libavfilter     7.110.100
   libswresample   3.9.100
FFmpeg version: n4.4

On arch linux. Reproducible with both pacakged mpv and built from git.
Using intel GPU with x11.

Reproduction steps

Run mpv --no-config --saturation=x --hue=y some_image.png.
The output looks the same no matter the value of x or y.
Note that the issue does not occur with videos, only images.
Changing the value at runtime (with the default keys 7 or 8) also has no effect.

The brightness, contrast and gamma controls are not affected, and behave as expected

Expected behavior

The hue and saturation value are applied.

Actual behavior

The image is displayed, as if hue and saturation were set to 0.

Log file

log.txt

Start by reproducing the issue with the provided mpv command and compare the image-processing path with video playback, since the problem is limited to image files. Done means hue and saturation affect displayed images at startup and when changed at runtime, while brightness, contrast, and gamma continue to work.