[1.21.3] GUI RenderSystem#setShaderColor Issues

[Stav]

Hello all,

I recently tried to upgrade my Minecraft mod to version 1.21.3, and I seem to have a problem with the `RenderSystem#setShaderColor` method.

Here is how the screen is usually supposed to look like:



Here is how it looks at present:

To further explain, the note labels atop of the note buttons are colored cyan (here) using `RenderSystem#setShaderColor`. The note buttons and labels get their colors from their native texture - white.

This means that even though I set the coloring to apply to the label (top), it is applied to the button (bottom).

What I conclude is happening then, in essence, is that this method (at least for my case) does not color the blit after - but rather the blit before..? 
This also blocks me from later resetting the shader, as I need to set it back to white before the blitting is done, and not when it's done. So like... what?

I've tested this further with other components that require this method, and this preceding-like behavior seems to be pretty consistent for them too.

 

I should mention that all the snippets I am about to show have all worked in past versions.

In my class `ClientUtil`, the following methods are defined:

    public static void setShaderColor(final Color color, final float alpha) {
        RenderSystem.setShaderColor(
            color.getRed() / 255f,
            color.getGreen() / 255f,
            color.getBlue() / 255f,
            alpha
        );
    }
    public static void setShaderColor(final Color color) {
        setShaderColor(color, 1);
    }
    public static void resetShaderColor() {
        setShaderColor(Color.WHITE);
    }

    //...

    public static RenderType guiRT(final ResourceLocation loc) {
        return RenderType.guiTextured(loc);
    }

And here is the snippet from `NoteButtonRenderer#renderNote` using it:

    // "Note" here refers to those symbols in the middle of a note button
    protected void renderNote(final GuiGraphics gui, final InstrumentThemeLoader themeLoader) {
        final int noteWidth = noteButton.getWidth()/2, noteHeight = noteButton.getHeight()/2;
        
        ClientUtil.setShaderColor((noteButton.isPlaying() && !foreignPlaying)
            ? themeLoader.notePressed()
            : themeLoader.noteReleased()
        );

        gui.blit(ClientUtil::guiRT,
            noteTextureProvider.get(),
            noteButton.getX() + noteWidth/2, noteButton.getY() + noteHeight/2,
            0, 0,

            noteWidth, noteHeight,
            noteWidth, noteButton.getHeight()/2
        );

        ClientUtil.resetShaderColor();
    }

You may find the full source here.

The odd thing is that Minecraft does seem to use this method the regular way I showed, for instance `SkyRenderer#renderSkyDisc` (not sure if I'l allowed to paste it).

Could it be that I'm doing something wrong that leads to this issue..? I'm really stumped on this one. 
I couldn't really find any change logs or documentation for this rendering API (even in this Fabric blog post), so I'm sorry if this seems obvious or anything. 
Either way, any help would be appreciated.