### 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
shadow_render.shader.version_set_uniform(CanvasOcclusionShaderGLES3::MODELVIEW1, modelview.columns[0][0], modelview.columns[1][0], 0, modelview.columns[2][0], shadow_render.shader_version, variant);
		shadow_render.shader.version_set_uniform(CanvasOcclusionShaderGLES3::MODELVIEW2, modelview.columns[0][1], modelview.columns[1][1], 0, modelview.columns[2][1], shadow_render.shader_version, variant);
		if (co->cull_mode != cull_mode) {
			if (co->cull_mode == RS::CANVAS_OCCLUDER_POLYGON_CULL_DISABLED) {
				glDisable(GL_CULL_FACE);
			} else {
				if (cull_mode == RS::CANVAS_OCCLUDER_POLYGON_CULL_DISABLED) {
					
					glEnable(GL_CULL_FACE);
				}
				glCullFace(co->cull_mode == RS::CANVAS_OCCLUDER_POLYGON_CULL_CLOCKWISE ? GL_FRONT : GL_BACK);
			}
			cull_mode = co->cull_mode;
		}
		glBindVertexArray(co->vertex_array);
		glDrawElements(GL_TRIANGLES, 3 * co->line_point_count, GL_UNSIGNED_SHORT, 0);
		instance = instance->next;
	}
	Transform2D to_shadow;
	to_shadow.columns[0].x = 1.0 / -(half_size * 2.0);
	to_shadow.columns[2].x = 0.5;
	cl->shadow.directional_xform = to_shadow * to_light_xform;
	glBindVertexArray(0);
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	glDepthMask(GL_FALSE);
	glDisable(GL_DEPTH_TEST);
	glDisable(GL_SCISSOR_TEST);
	glDisable(GL_CULL_FACE);
}
void RasterizerCanvasGLES3::_update_shadow_atlas() {