1. Locate the txt file in the Unity installation directory\2020.3.18f1c1\Editor\Data\Resources\ScriptTemplates directory
Open the 81-C# Script-NewBehaviourScript.cs.txt file with Notepad and save it as UTF-8 (the default is UTF-8 + BOM(byte order mark))
2. If the script is written by Visual Studio, the encoding format can be modified
Menu bar--File--Advanced Save Options-- Unicode (UTF-8 with signature) code page 65001
If you can't find the advanced save option in the file bar, you can add it
The method of adding is as follows
Tools - Customize - Command - Menu Bar - File - Add Command - File - Advanced Save Options - OK