### 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
ERR_FAIL_COND(rt->sdf_texture_write_fb != 0);
	Size2i size = _render_target_get_sdf_rect(rt).size;
	glGenTextures(1, &rt->sdf_texture_write);
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, rt->sdf_texture_write);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, size.width, size.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
	GLES3::Utilities::get_singleton()->texture_allocated_data(rt->sdf_texture_write, size.width * size.height, "SDF texture");
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 1);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glGenFramebuffers(1, &rt->sdf_texture_write_fb);
	glBindFramebuffer(GL_FRAMEBUFFER, rt->sdf_texture_write_fb);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, rt->sdf_texture_write, 0);
	int scale;
	switch (rt->sdf_scale) {
		case RS::VIEWPORT_SDF_SCALE_100_PERCENT: {
			scale = 100;
		} break;
		case RS::VIEWPORT_SDF_SCALE_50_PERCENT: {
			scale = 50;
		} break;
		case RS::VIEWPORT_SDF_SCALE_25_PERCENT: {
			scale = 25;
		} break;