I have a resource pack which changes the texture of the appleskin saturation overlay.
The following image is located in [resource_pack]/assets/appleskin/textures/icons.png

This worked fine in 1.19.3, but after updating my game and mods, I no longer see the custom texture in game:

Forge or Fabric?

Fabric

Can't reproduce this. The following resource pack works for me locally:

test.zip

Had similar issue with the saturation texture but with 1.21 Fabric and found out it was a mod called "paxi" that "broke" it. I didnt actually try it but I believe you can fix it by putting your textures into paxi, if it still doesnt work just remove paxi.