Pyright strict type-checking mode won't work in Sublime Text 4.0

I have installed LSP and LSP-pyright in Sublime Text 4 and included "python.analysis.typeCheckingMode": "strict" within the LSP-pyright.sublime-settings file but Pyright still won't raise any Type error when I wrote the following code:

def foo(x, y):
    return x + y

To add, it seems the basic type-checking mode still work since the code

import unknownpackage

makes Pyright raise reportMissingImports. So what seems to be the problem?