Reproduction steps:
1. Open the attached project “TextureImportIssue”
2. Select the “Assets/textures.tga” texture
3. In the Menu bar click on Test > ConvertToRGBA
4. Select the “Assets/textures.tga._autogen.tga” texture and compare it to “textures.tga”

Expected result: Both textures look identical
Actual result: The “textures.tga._autogen.tga” texture looks different from the “textures.tga” texture

Reproducible with: 2022.3.7f1, 2023.1.10f1, 2023.2.0b6, 2023.3.0a2
Couldn’t test with: 2021.3.29f1 - errors in user script: “TextureImporterSettings' does not contain a definition for 'swizzleA' and no accessible extension method 'swizzleA' accepting a first argument of type 'TextureImporterSettings' could be found (are you missing a using directive or an assembly reference?)”

Reproducible on: macOS 13.4.1 (c)
Not reproducible on: No other environments tested