### Godot version

v4.0.beta17.official [c40020513]

### System information

Windows 11, OpenGL (Compatibility), RTX 2060 (31.0.15.2824)

### Issue description

I tried to make a blurred panel for a ui element with texturelod via shader:

```glsl
shader_type canvas_item;

uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap_anisotropic;
uniform float blur_amount : hint_range(0.0, 5.0);

void fragment() {
	vec4 blurred = textureLod(SCREEN_TEXTURE, SCREEN_UV, blur_amount);
	COLOR = blurred;
}
```

but what I got instead is this:
![image](https://user-images.githubusercontent.com/72286622/217170426-49f6712d-47ef-4c53-b9f1-30d8ad868084.png)

vulkan renderer does not exhibit this issue:
![image](https://user-images.githubusercontent.com/72286622/217170565-a013c712-94f6-49d1-b9ec-091c28a7790b.png)


### Steps to reproduce

1. Add a TextureRect node
2. Add a Panel node to overlay the previously added node
3. Apply the blur shader to the panel node

### Minimal reproduction project

N/A
case Image::FORMAT_ETC2_RA_AS_RG:
		case Image::FORMAT_DXT5_RA_AS_RG: {
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_R, GL_RED);
			if (texture->format == real_format) {
				
				glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_G, GL_ALPHA);
			} else {
				
				glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_G, GL_GREEN);
			}
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_B, GL_ZERO);
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_A, GL_ONE);
		} break;
		default: {
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_R, GL_RED);
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_G, GL_GREEN);
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_B, GL_BLUE);
			glTexParameteri(texture->target, GL_TEXTURE_SWIZZLE_A, GL_ALPHA);
		} break;
	}
#endif 
	int mipmaps = img->has_mipmaps() ? img->get_mipmap_count() + 1 : 1;
	
	if (mipmaps > 1) {
		texture->gl_set_filter(RS::CANVAS_ITEM_TEXTURE_FILTER_NEAREST_WITH_MIPMAPS);
	} else {
		texture->gl_set_filter(RS::CANVAS_ITEM_TEXTURE_FILTER_NEAREST);
	}
	texture->gl_set_repeat(RS::CANVAS_ITEM_TEXTURE_REPEAT_ENABLED);
	int w = img->get_width();