I have fairly new (2 months old) Samsung Galaxy Buds+ (6DEC) and I have never been able to get the case to wireless charge consistently. I am using the with a Samsung wireless charger (Model: EP-P3105) that came with the headphones (Samsung bundle deal).
Both the charger and the case have a red light when the case is centered on the charger, but there appear to be many times the battery % as reported on my phone doesn't increase.
Again though, it sometimes works and sometimes doesn't (inconsistent).
I am using a Samsung wall adapter and have tested both wall adapter models I have (EP-TA800 and EP-TA200).
EP-P3105: Wireless Charger Pad
EP-TA800: Samsung 25W USB-C Super Fast Charging Wall Charger
EP-TA200: Samsung Fast Charge USB-C 15W Wall Charger