### 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 
progress_delay = p_delay_ms;
}
int RichTextLabel::get_progress_bar_delay() const {
	return progress_delay;
}
bool RichTextLabel::_validate_line_caches() {
	if (updating.load()) {
		return false;
	}
	validating.store(true);
	if (main->first_invalid_line.load() == (int)main->lines.size()) {
		MutexLock data_lock(data_mutex);
		Rect2 text_rect = _get_text_rect();
		int ctrl_height = get_size().height;
		
		float old_scroll = vscroll->get_value();
		if (main->first_invalid_font_line.load() != (int)main->lines.size()) {
			for (int i = main->first_invalid_font_line.load(); i < (int)main->lines.size(); i++) {
				_update_line_font(main, i, theme_cache.normal_font, theme_cache.normal_font_size);
			}
			main->first_resized_line.store(main->first_invalid_font_line.load());
			main->first_invalid_font_line.store(main->lines.size());
		}
		if (main->first_resized_line.load() == (int)main->lines.size()) {
			vscroll->set_value(old_scroll);
			validating.store(false);
			return true;
		}