### Godot version

master ([06ccbfe](https://github.com/godotengine/godot/commit/06ccbfe8eec6e840db3df2360dc2804386f940b8))

### System information

PopOS 22.04

### Issue description

Sometimes the doc page is broken when the engine is closed and then restarted.
Closing the doc and opening it again fixes it.

![2023-05-27_22-15](https://github.com/godotengine/godot/assets/3624853/ed202a55-03e8-420a-bc1c-ccfc7f7cd02a)


### Steps to reproduce

- Open a documentation page for any node
- Restart Godot

### Minimal reproduction project

NA

EDIT : Added the commit hash @Calinou 
if (visible_ratio != p_ratio) {
		_stop_thread();
		if (p_ratio >= 1.0) {
			visible_characters = -1;
			visible_ratio = 1.0;
		} else if (p_ratio < 0.0) {
			visible_characters = 0;
			visible_ratio = 0.0;
		} else {
			visible_characters = get_total_character_count() * p_ratio;
			visible_ratio = p_ratio;
		}
		if (visible_chars_behavior == TextServer::VC_CHARS_BEFORE_SHAPING) {
			main->first_invalid_line.store(0); 
			_validate_line_caches();
		}
		queue_redraw();
	}
}
float RichTextLabel::get_visible_ratio() const {
	return visible_ratio;
}
void RichTextLabel::set_effects(Array p_effects) {
	custom_effects = p_effects;
	if ((!text.is_empty()) && use_bbcode) {
		parse_bbcode(atr(text));
	}
}
Array RichTextLabel::get_effects() {