Start with the real service area
Why Peacock blocks playback outside the US
Peacock's own availability page limits the service to the United States and five US territories. Unlike Prime Video, Peacock does not switch to a local catalogue when you cross a border; it can stop the session because the detected network country is outside its service area.
That first decision is network-based, but it is not the only one. An old browser cookie can retain a prior region, a mobile app can keep cached account state, and a television can use a different network path from the computer you tested.
The useful distinction: a location message before normal playback usually points to the network or session. A checkout rejection, missing app or unavailable event belongs to the account, store or rights layer and should be diagnosed separately.