### Godot version

4.1.1.stable, 4.2.dev (2282fc5de)

### System information

Arch Linux - X11 - GLES3 (Compatibility) - NVIDIA GeForce RTX 3060 Ti (nvidia; 535.104.05) - 13th Gen Intel(R) Core(TM) i5-13400F (16 Threads)

### Issue description

When using Compatibility renderer, adjusting the Alpha component of clear color affects 2D editor content.

This does not happen when using Forward+ or Mobile renderer. Does not affect 3D editor and the running game.


https://github.com/godotengine/godot/assets/372476/e398522e-590a-4832-959f-ea8ba8e71c5d



### Steps to reproduce

1. Create a project using Compatibility renderer.
2. Adjust the clear color's alpha component in Project Settings.

### Minimal reproduction project

N/A
OccluderPolygon occluder;
	return occluder_polygon_owner.make_rid(occluder);
}
void RasterizerCanvasGLES3::occluder_polygon_set_shape(RID p_occluder, const Vector<Vector2> &p_points, bool p_closed) {
	OccluderPolygon *oc = occluder_polygon_owner.get_or_null(p_occluder);
	ERR_FAIL_COND(!oc);
	Vector<Vector2> lines;
	if (p_points.size()) {
		int lc = p_points.size() * 2;
		lines.resize(lc - (p_closed ? 0 : 2));
		{
			Vector2 *w = lines.ptrw();
			const Vector2 *r = p_points.ptr();
			int max = lc / 2;
			if (!p_closed) {
				max--;
			}
			for (int i = 0; i < max; i++) {
				Vector2 a = r[i];
				Vector2 b = r[(i + 1) % (lc / 2)];
				w[i * 2 + 0] = a;
				w[i * 2 + 1] = b;