[Python] mypy: Collection[str] replaces nested structure typing?

I have a data variable that, if typed properly, should look like this:

data: List[Dict[str, Union[str, Dict[str, List[Dict[str, str]]]]]] = []


But when I try to append to this list with the following code:

info = {"spaghetti": [{"value": "foo", "test": "bar"}]}
my_data = {
"Name": name,
"_info": info,
}
data.append(my_data)


Mypy tells me:

Argument 1 to "append" of "list" has incompatible type "Dict[str, Collection[str]]"; expected "Dict[str, Union[str, Dict[str, List[Dict[str, str]]]]]"


Now, how is that possible that Union[str, Dict[str, List[Dict[str, str]]]] is equivalent to a Collection[str] ?

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