Python does not perform static type checking, therefore this problem doesn't apply immediately. You can build a program that takes exponential time to execute, but that is probably not a relevation to you.
I don’t think that’s possible because I don’t think there’s any aspect of the runtime type checker that descends into complex type structures. It just checks if runtime type tags match when you invoke an operator, or that an attribute exists when you try to access it.
There may be some kind of linter that would choke on type inference, but I think you are correct. It is more a just in time type inference at runtime otherwise.