bafang bbso2

I just noticed a sound coming from the motor. It does not sound that loud or even cannot be heard while riding but I just got worried. Does anyone had an issue like this? What is the problem and the solution? Thanks in advance to everyone Youtube link:

I ride a Yuba Mundo Lux cargo bike and after a couple of years pulling the kids around on it, added a bafang bbso2 to help with the weight. Overall it has been great but definitely notice the bafang is hard on the bike and wears on everything from my drivetrain to brakes and front hub. Love my...