Can't load textures in gray color space

[passivestar]

Tested versions

v4.3.dev6.official [89850d5]

System information

Godot v4.3.dev6 - macOS 14.4.1 - Vulkan (Forward+) - integrated Apple M1 Max - Apple M1 Max (10 Threads)

Issue description

This is what macos tells me about them:

RGB textures load with no problem

Steps to reproduce

Unfortunately I can't share the images because of their license

I couldn't reproduce this issue when exporting an image from affinity photo with these parameters:

Will make an MRP if I manage to find public domain textures that have this problem

Minimal reproduction project (MRP)

N/A