Ring Video Doorbell 2 draining while hardwired

Hello, I have a Ring Video Doorbell 2 that's always been hardwired to a 20VAC transformer since I got it in 2018. Until the past couple months, I have never had to charge it, but recently the battery has been draining even without any change in the average number of motion events. If I take out the battery and plug it back in to "restart" the doorbell, it starts charging again slowly at a rate of about 8-10% charge per day. However, seemingly at random it will start draining quickly again at a rate of 15-20% per day. One time I tested the doorbell, it got back up to 44% before it started draining. Another time it got all the way up to 100% before it started draining again 1-2 days later. It seems like maybe there's a software bug that randomly triggers and then goes away temporarily after a reboot. At first I attributed the battery drain to the cold since it first died when it was in the 10s and 20s Fahrenheit outside, so I took it inside and charged it, but now that the weather has warmed up, it's still having the same issue. I connected the doorbell directly to the 20VAC transformer and bypassed my doorbell chime to make sure that's not causing an issue. I measured the voltage from the transformer at the connections to the doorbell at 21VAC. But still having the same problem after doing that. Any suggestions would be greatly appreciated. Thank you! Mike