### Godot version

4.0.3-stable

### System information

Windows 10

### Issue description

In some projects ViewportTexture remains pink and doesn't render viewport content after upgrading from 4.0.2-stable to 4.0.3-stable. If a pair of files viewport.h/viewport.cpp are downgraded back to what they were in 4.0.2-stable, problem goes away.

This is how it looks in 4.0.3-stable:
![4 0 3_stable_viewport_4 0 3](https://github.com/godotengine/godot/assets/1449921/44c191a9-4b67-4b02-90b6-4ab615f62a73)

And this is how it looks if viewport.h/viewport.cpp are downgraded back to what they were in 4.0.2-stable.
![4 0 3_stable_viewport_4 0 2](https://github.com/godotengine/godot/assets/1449921/f5abc605-f129-4222-9c0e-e9a07621dd9d)



### Steps to reproduce

Unfortunately, I cannot come up wit a simple demo project reproducing the problem. It exists in some projects and doesn't exist in others.


### Minimal reproduction project

Cannot produce a simple project reproducing the problem. In simple projects it works fine.
ERR_READ_THREAD_GUARD_V(0);
	return positional_shadow_atlas_size;
}
void Viewport::set_positional_shadow_atlas_16_bits(bool p_16_bits) {
	ERR_MAIN_THREAD_GUARD;
	if (positional_shadow_atlas_16_bits == p_16_bits) {
		return;
	}
	positional_shadow_atlas_16_bits = p_16_bits;
	RS::get_singleton()->viewport_set_positional_shadow_atlas_size(viewport, positional_shadow_atlas_size, positional_shadow_atlas_16_bits);
}
bool Viewport::get_positional_shadow_atlas_16_bits() const {
	ERR_READ_THREAD_GUARD_V(false);
	return positional_shadow_atlas_16_bits;
}
void Viewport::set_positional_shadow_atlas_quadrant_subdiv(int p_quadrant, PositionalShadowAtlasQuadrantSubdiv p_subdiv) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_INDEX(p_quadrant, 4);
	ERR_FAIL_INDEX(p_subdiv, SHADOW_ATLAS_QUADRANT_SUBDIV_MAX);
	if (positional_shadow_atlas_quadrant_subdiv[p_quadrant] == p_subdiv) {
		return;
	}
	positional_shadow_atlas_quadrant_subdiv[p_quadrant] = p_subdiv;
	static const int subdiv[SHADOW_ATLAS_QUADRANT_SUBDIV_MAX] = { 0, 1, 4, 16, 64, 256, 1024 };
	RS::get_singleton()->viewport_set_positional_shadow_atlas_quadrant_subdivision(viewport, p_quadrant, subdiv[p_subdiv]);
}
Viewport::PositionalShadowAtlasQuadrantSubdiv Viewport::get_positional_shadow_atlas_quadrant_subdiv(int p_quadrant) const {