Add 5th Yarwin suggestion:

"Use i32/u32 instead. In original demo it is just an Int: https://github.com/godotengine/godot-demo-projects/blob/4.2-31d1c0c/3d/squash_the_creeps/ScoreLabel.gd"

Author: FrankCasanova

squash-the-creeps/rust/src/scorelabel.rs

@@ -4,15 +4,15 @@ use godot::prelude::*;
 #[derive(GodotClass)]
 #[class(init, base=Control)]
 pub struct UserInterface {
-    score: f32,
+    score: u32,
     base: Base<Control>,
 }
 
 #[godot_api]
 impl UserInterface {
     #[func]
     pub fn on_mob_squashed(&mut self) {
-        self.score += 1.0;
+        self.score += 1;
 
         let mut label = self.base().get_node_as::<Label>("ScoreLabel");
         label.set_text(format!("Score: {}", self.score).as_str());