### 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
String global_defines;
	global_defines += "#define MAX_GLOBAL_SHADER_UNIFORMS 256\n"; 
	global_defines += "#define MAX_LIGHTS " + itos(data.max_lights_per_render) + "\n";
	GLES3::MaterialStorage::get_singleton()->shaders.canvas_shader.initialize(global_defines, 1);
	data.canvas_shader_default_version = GLES3::MaterialStorage::get_singleton()->shaders.canvas_shader.version_create();
	state.shadow_texture_size = GLOBAL_GET("rendering/2d/shadow_atlas/size");
	shadow_render.shader.initialize();
	shadow_render.shader_version = shadow_render.shader.version_create();
	{
		default_canvas_group_shader = material_storage->shader_allocate();
		material_storage->shader_initialize(default_canvas_group_shader);
		material_storage->shader_set_code(default_canvas_group_shader, R"(
// Default CanvasGroup shader.
shader_type canvas_item;
render_mode unshaded;
uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;
void fragment() {
	vec4 c = textureLod(screen_texture, SCREEN_UV, 0.0);
	if (c.a > 0.0001) {
		c.rgb /= c.a;
	}
	COLOR *= c;
}
)");
		default_canvas_group_material = material_storage->material_allocate();
		material_storage->material_initialize(default_canvas_group_material);
		material_storage->material_set_shader(default_canvas_group_material, default_canvas_group_shader);
	}
	{
		default_clip_children_shader = material_storage->shader_allocate();