OYMA POWER Folding Mountain Bike

This is a black folding mountain bike. It features a sturdy frame and disc brakes for reliable stopping power. It's a great option for commuting or recreational riding. The only concern is that when I put heavy pressure on the pedals,, they suddenly slip forward with no resiatance, it feels like the drive train is losing engagement. It could possibly be caused by poor derailleur alignment or adjustment, but I think it may be fixable. I would just want to have the drivetrain checked to make sure there isn't any issue with the chain, cassette,derailleur,or freehub.It is called ghost pedaling, chain skipping, or a freehub slip!