### 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
}
		texture->is_render_target = true;
		texture->render_target = rt;
		if (rt->overridden.color.is_null()) {
			texture->format = rt->image_format;
			texture->real_format = rt->image_format;
			texture->target = texture_target;
			if (rt->view_count > 1 && config->multiview_supported) {
				texture->type = Texture::TYPE_LAYERED;
				texture->layers = rt->view_count;
			} else {
				texture->type = Texture::TYPE_2D;
				texture->layers = 1;
			}
			texture->gl_format_cache = rt->color_format;
			texture->gl_type_cache = GL_UNSIGNED_BYTE;
			texture->gl_internal_format_cache = rt->color_internal_format;
			texture->tex_id = rt->color;
			texture->width = rt->size.x;
			texture->alloc_width = rt->size.x;
			texture->height = rt->size.y;
			texture->alloc_height = rt->size.y;
			texture->active = true;
		}
	}
	glClearColor(0, 0, 0, 0);
	glClear(GL_COLOR_BUFFER_BIT);
	glBindFramebuffer(GL_FRAMEBUFFER, system_fbo);
}
void TextureStorage::_create_render_target_backbuffer(RenderTarget *rt) {