Google Nest Doorbell - Battery Died

I have the Google Nest Doorbell (battery version) at a short term rental property that has worked great for the past 3 years or so.

Today I went to pull up the camera on my Google Home app, and it's saying the battery is empty. I stopped re-charging it because it's hardwired to the doorbell and it always seemed to maintain 70% or so charge. But for whatever reason it's now dead, and the fact that it's hardwired doesn't seem to matter.

Is this expected behavior? Do I need to plan to pull it off the mount a couple times a year to plug it into a USB C charger? Or is there something else going on here?

On my next visit I'll probably just swap it over to the wired version (no battery) because I prefer the 24/7 vs event only recording anyway (and I already pay for the larger plan because of another camera). In the meantime I guess I'm without this camera until my next visit, unless anyone has any suggestions.