Quick answer: Godot 4 Tween with TRANS_QUART and EASE_OUT overshooting the target value? Easing function returns >1.0 on edge cases - clamp or use TRANS_QUAD.
Tween a position from 0 to 100 with QUART OUT. Final value briefly hits 100.5 then settles.
Use TRANS_QUAD
Quad doesn't overshoot. Visually similar; numerically stable.
Or clamp the final value
Connect tween_method: clamp the output. Defensive; works with any trans/ease.
Use bounce/elastic intentionally
If you want overshoot, BOUNCE and ELASTIC are designed for it. QUART overshoots accidentally.
“Easing functions are mathematical. Some return values outside [0,1].”
Document which trans/ease combos are 'safe' (no overshoot) in your project. Designers reach for the right ones; bugs avoid.