It chooses the challenge weight based on signals. If your phone looks like a phone from a residential IP you get a simple challenge. If you then spam requests

It chooses the challenge weight based on signals. If your phone looks like a phone from a residential IP you get a simple challenge. If you then spam requests you might get another, harder, hallenge appear. If you have a data center IP and look like bot traffic you get a hard challenge out the gate. AFAIU after looking at their docs several months ago.