What factors could cause wrist injury for tennis?

Various: Repetitive motion and strong torquing movements cause most injuries. You can also do like me and chase ball off the court onto wet grass and break your wrist :).

Falling or snapping: The major cause of wrist injury in tennis is falling or snapping your wrist writh serving or spinning the ball. If you have an injury to your wrist see a hand surgeon.

Awkward stroke.: An awkward stroke can result in poor mechanics, that can cause wrist injury. Improving your tennis skills, to transfer force to the face of your racket, can help prevent these injuries.