Liberty Air battery indicator issues

Hi, I’ve been using the Soundcore Liberty Air for about 2 weeks now and noticed a problem with the earbuds’ charge indicator.
I make sure the earbuds’ charge indicates 100% on the phone before going to bed. When I leave it overnight or over 5~6 hrs in the case and then take it out the battery indicator says 50~60%. I know this isn’t a cleaning issue because it was there from the beginning when I bought it, I just had to check a few times overnight to confirm it was the earbuds’ problem and not the case’s. Connectivity problem seems unlikely too, since the earbuds do charge.

Is this a problem I can fix or should I return it under warranty ?