Cyprus Airways power-bank flight policy.

Short answer

Cyprus Airways publishes an official baggage-page safety notice for lithium batteries and power banks. The page states that power banks/lithium batteries must be carried in cabin baggage or on the passenger only, are strictly prohibited in checked baggage, are limited to a maximum of two per passenger, each is allowed up to 100 Wh while 100-160 Wh requires approval, over 160 Wh is not permitted, and units must be protected from short circuit. It also prohibits using power banks to charge devices, prohibits charging power banks from aircraft USB/outlets, requires power banks to remain switched off throughout the flight, and requires stowage on the person, in the seat pocket, or under the seat rather than in overhead bins.