This was probably a result of privacy concerns. The minimum in the API specification could be even much smaller, but the implementer must be made aware of legal implications and define a minimum for their use case.

I'm fine to shift from 2000 to 1 but we need to add a note in the documentation part of the API specification to clearly indicate that the area surface could be restricted locally depending on regulation (eg. the yaml specify a minimum of 1 but an implementation could restrict to a minimum of 1000).

For location-verification we probably need to define an error to manage this case (an implementation restricts the value above 1000 and got 150 in the request). We can use 422 + AREA_NOT_COVERED (as defined in geofencing).

I agree, that we need to indicate that implementations may consider a minimum radius as valid input, due to privacy or implementation constraints, and as @bigludo7 proposes, define a specific error to signal that the input area is not supported,