The problem that PHP's putenv function cannot be used in Chinese

If you know laravel, you can take a look at the above section; if you don’t, just go straight below the dividing line;

Any item in .env, here is MAIL_DRIVER as an example
Change it to "my" and use the env function, and you can get the value normally;
Change it to "I" and use the env function, and you can't get it normally;

<code>MAIL_DRIVER=我
var_dump(env(MAIL_DRIVER''));  // NULL


MAIL_DRIVER=我的
var_dump(env(MAIL_DRIVER''));  // 我的</code>

This situation will also occur with other Chinese words such as "good";
I have to say; laravel is broad and profound; I have studied the source code of the env function;
The problem I finally identified is;
--------- ----------------------------------------Understand and understand the dividing line between laravel framework- --------------------------------------------------

<code>putenv("PROJECT_NAME=我的");
phpinfo();</code>

You can search for PROJECT_NAME in Environment in phpinfo

<code>putenv("PROJECT_NAME=我");
phpinfo();</code>

Project_NAME cannot be found in Environment in phpinfo

Dear friends, why is this? How to set Chinese value without any problem?