The recent bans are coming from a flaw in Niantic’s ban system where the system is banning from a variety of reports. Meaning that, you have to be reported by 3 separate people to be banned.
Until this is resolved and Niantic further provides us a statement, I cannot advise you to put Pokemon in your gyms for the sake of not being banned. Those who are traveling are also randomly receiving a ban from the API. The system is all messed up right now and you guys should be alert about this. DO NOT Put Your Pokemon In Gyms until a statement is issued by Niantic saying otherwise. If this article helped save your account, then please like our Pokemon Go Fan Page!