Expected lifespan of doorbell battery?

I have two Video Doorbell 2 devices and 3 batteries. I have the third so that the doorbell can be powered up while a depleted battery is charging. We live in the Midwest, so all kinds of temperatures. It is not hardwired, but both have the small solar panel base attached. I usually get alerts to my phone and email about once per month as they drop to 30% charge. One of the batteries did not alert until 5% last time around, and nearly immediately after that, the doorbell powered down, no warning. I recharged the battery, and the next time I used it, it would not power up either doorbell. The other two batteries still work just fine. So, my question is, how many years lifespan should I expect of the battery before it is no longer effective? Is it expected that a battery in service since about 2019 would reach end-of-life by now or could something else be wrong?