Yamaha X Max 250 Making Rattling Noise Uphill with Two Riders

I have a 2024 Yamaha X Max 250 with 8,500 km on it, and I’ve started noticing a rattling noise coming from the back when riding uphill with two people. The noise sounds like a sewing machine at work. There’s no issue when riding solo, but this buzzing sound is really bothering me. The scooter is still under warranty, and I’ve scheduled a service appointment, but it’s a week away. Does anyone have any insights or advice on what could be causing this issue? I would appreciate any guidance while I wait for my appointment.