AirPods 3 buzzing/hissing sound in left bud

I recently brought AirPods 3 and paired it with my 13 pro max, which on the 4th day of use caused a problem where the RIGHT BUD WAS NOT DETECTING/CHARGING when placed inside case. So i contacted apple support and they advised me to take it to apple service provider. So i took it to service and since i was covered with warranty i got my case replaced, which took 2 weeks.

The very next day after i got my AirPods back from service with case replaced, Another issue pops up, where i get a mild BUZZING/HISSING SOUND FROM LEFT BUD when i place it in my ear without playing any music or calls , also when placed inside the case with the buds charged 100% the BATTERY OF THE CASE DRAINS VERY FAST , like 3% for every 20 minutes even if i don’t use it and even I tried turning off Bluetooth in my phone and the charge was still decreasing.

So I contacted apple support, they told to try pairing with some other device and the problem persists even when i did so. So final option apple support gave was take it back again to apple service provider.

The service technician after examining the AirPods for 3 days calls me to tell “there is no issue with the device, you may come and collect it”.

I collected it, But still the buzzing at left pod continues and charge at case decreasing even when not in use.

Any ideas on how to fix this issue..??