Regulation
A broker being supervised by a financial authority (FCA, CySEC, ASIC, the Capital Markets Board of Turkey (SPK)…); it means client funds are held in a separate account and there is a complaints mechanism.
Strong authorities (FCA, ASIC, CySEC, BaFin) set requirements for capital adequacy, segregation of funds and compensation schemes. Offshore licenses (St. Vincent, Seychelles) allow higher leverage but protection is weak.
The same brand can operate through several companies under different licenses; check which legal entity your account is opened with.