Pydantic V2 allow validator to annotate potential input argument types

Question

With a Pydantic V2 BaseModel, I'm trying to allow multiple data types to be input but are parsed to a specific type via @field_validator. For example:

from typing import Iterable

class Example(BaseModel):
    my_string: str   # Will always become str due to field_validator
    
    @field_validator('my_string', mode='before')
    @classmethod
    def parse_my_string(cls, value: str | Iterable[str]) -> str:   # Allow both str and Iterable[str]
        if isinstance(value, str):
            return value
        else:
            return ', '.join(value)

but now if I try to instantiate it with an Iterable, it (Pylance) gives me red squigglies:

Example(my_string=['A', 'B', 'C'])

Argument of type "list[str]" cannot be assigned to parameter "my_string" of type "str" in function "init" "list[str]" is incompatible with "str" Pylance(reportArgumentType)

How can I make it look to the field_validator method for potential input types?

I would hope/expect that validators can be checked for potential input argument types.