There are several reasons why bet365 accounts can be restricted, including matched betting, unreasonable betting behaviour, GamStop (self-exclusion), and exploitation of bonuses.
bet365 is only available in licensed countries such as the UK, Australia, Germany, and others. To enforce licensing agreements, it regularly checks users' IP addresses to determine their location. If bet365 sees you're from a country where the service is unavailable, they'll block your access.