I was going to report that to #13592, but I figured I should start a separate issue.

Another good example: https://mypy-play.net/?mypy=latest&python=3.11&gist=be72c683d77ea7655f78aa56f603e689
This gist is the same as https://github.com/Keyacom/small-python-projects/blob/main/fire-tools/expcalc.py, except that I removed the type: ignore comment on line 72.
Here, mypy fails to acknowledge the fact any code beyond sys.exit() is not reachable. Pyright also behaves like this.
In lines 62~65, I'm not allowing chal, level, or fb to be None. They're initialized as None, but they can be fetched from command line arguments:

    if any(x is None for x in (chal, level, fb)):
        print("Incomplete arguments.")
        print(USAGE)
        exit(2)

This later causes errors on line 72:

        calc_exp(fb, chal, level)

with the mypy output:

main.py:72: error: Argument 1 to "calc_exp" has incompatible type "int | None"; expected "int"  [arg-type]
main.py:72: error: Argument 2 to "calc_exp" has incompatible type "int | None"; expected "int"  [arg-type]
main.py:72: error: Argument 3 to "calc_exp" has incompatible type "int | None"; expected "int"  [arg-type]
Found 3 errors in 1 file (checked 1 source file)

For reference, here's calc_exp's signature:

def calc_exp(fb: int, chal: int, level: int) -> int:
    ...

NOTE: If I change line 62 to the one below, there are no errors. It's just more verbose.

    if chal is None or level is None or fb is None:

Err, I don't think any narrows to begin with. Normally, narrowing does happen if you exit:

from sys import argv, exit

def some_function(arg: int) -> int:
    return arg

num = None

try:
    num = int(argv[1])
except ValueError:
    pass

if num is None:
    exit(2)

print(some_function(num))

(notice the slightly modified if statement.)

This narrowing pattern is a little complex, I'd recommend using a PEP 647 typeguard. I'm not aware of any other Python static type checker that narrows like this.