Make stuff not public if it doesn't need to be

Assets/Scripts/ButtonTextColorSync.cs

@@ -1,10 +1,11 @@
+using System;
 using TMPro;
 using UnityEngine;
 
 public class ImageColorSync : MonoBehaviour
 {
-    public TMP_Text originalText;
-    public TMP_Text toSync;
+    [SerializeField] private TMP_Text originalText;
+    [SerializeField] private TMP_Text toSync;
 
     void Update()
     {