### 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 
Vector<String> subtag = tag.substr(5, tag.length()).split(" ");
			_normalize_subtags(subtag);
			int fs = theme_cache.normal_font_size * 3;
			Ref<Font> f = theme_cache.normal_font;
			Color color = theme_cache.default_color;
			Color outline_color = theme_cache.font_outline_color;
			int outline_size = theme_cache.outline_size;
			Rect2 dropcap_margins;
			for (int i = 0; i < subtag.size(); i++) {
				Vector<String> subtag_a = subtag[i].split("=");
				_normalize_subtags(subtag_a);
				if (subtag_a.size() == 2) {
					if (subtag_a[0] == "font" || subtag_a[0] == "f") {
						String fnt = subtag_a[1];
						Ref<Font> font = ResourceLoader::load(fnt, "Font");
						if (font.is_valid()) {
							f = font;
						}
					} else if (subtag_a[0] == "font_size") {
						fs = subtag_a[1].to_int();
					} else if (subtag_a[0] == "margins") {
						Vector<String> subtag_b = subtag_a[1].split(",");
						_normalize_subtags(subtag_b);
						if (subtag_b.size() == 4) {
							dropcap_margins.position.x = subtag_b[0].to_float();
							dropcap_margins.position.y = subtag_b[1].to_float();
							dropcap_margins.size.x = subtag_b[2].to_float();
							dropcap_margins.size.y = subtag_b[3].to_float();
						}
					} else if (subtag_a[0] == "outline_size") {