Not a Hubitat problem but something to keep in mind especially for those running smart devices at a vacation/remote property.
We had a power outage on Sunday and I shutdown the hub gracefully before the UPS ran out. When the power came back on many zigbee contact sensors and my Axis gear were no longer reporting to Hubitat. I'm guessing the hub being down for almost an hour caused the zigbee devices to panic which must have finished off many of the batteries as most of them hadn't been changed in a year or more. Many zigbee contacts and devices came back up just fine after the hub came back online so it wasn't all.
There were a couple of devices I just had to pull the battery and put it back in to get them working again but 12 or so had dead batteries. The two Axis gear shade controllers had to be taken out of smart control mode and put back in while detecting zigbee devices to re-join them to their existing objects.
I've been slowly wiring many devices to Konnected boards to eliminate batteries where I can but since the house was built before security systems were a thing there are many areas that are hard to get to and double-hung windows are much easier to detect with a single battery powered sensor verses two wired sensors.
Do you have battery monitoring set up in HSM? Might be better to flag that with notifications so that you can replace batteries as needed (like when they reach 20%) so you can keep ahead of things..
I do, only one was showing less than 20% before the power outage most were showing above 50%, with lithium batteries they often don’t show low battery until just before they die.
I took another approach - I have a battery backup for the Hub, my router, and a few other mission-critical devices (like my WaterCop shutoff valve), and I removed the stock brick-sized battery, and wired the thing to an old marine deep-cycle battery that sits on a shelf in the garage just below the pegboard to which the network gear is mounted. Even a worn-out car battery that someone turned in to the auto parts store (can be bought for a $5 bribe) will provide days of support for the small loads at issue. My goal here is to "survive" even a 2-day loss of power, and I can get at least 3 without bringing the battery down below 12 Volts. The idea here is to not loose the "security" of alerts on opened gate or windows just because power is out. My wife is very happy to be able to pull up a dashboard on her phone, and see doors locked, windows closed, etc even if we are lighting the stove with a lighter, and dining by candlelight.
