[Python] Why does my "defineConstant" in pyrightconfig.json not work in VSCode

In VSCode, my "defineConstant" does not work. For example,

"defineConstant": {
"__dev__": true,
},


But __dev__ in my code is still warning in VSCode. View problems:

"__dev__" is not defined Pylance(reportUndefinedVariable)
​

My Pylance's version is 2025.4.1.

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