Lily battery drain

I have been very happy with the Lily that I’ve bought for my partner, until recently when the battery started to drain like crazy.

It use to last the advertised 5 days, but now can barely make it through 2 days.

This problem also happened very suddenly and not like a gradual degradation of battery, so I suspect it has something to do with the new firmware. Currently on 6.20 btw.