I would use a name brand photo battery in this case. I always use lithium batteries where I can, such as Energizer ultimate lithium brand batteries in AA and AAAs. They far outlast alkaline batteries and handle cold conditions very well. But these are CR-2’s which should be lithium anyway.
I’ve seen people having problems with water leak sensors draining batteries it situations where they sensor is getting wet often, such as when monitoring sumps or even protein skimmers in aquarium applications.
They often get a lot of false positives after a while too.
The problem is that these are “metal probe” style sensors and they work by measuring the conductivity between the probes, much like an ohm meter. If there is something conductive between the probes, then current is flowing and if enough current is flowing it will of course trip the sensor. I would recommend cleaning the probe with some isopropyl alcohol, at least when you change the batteries as a bit of preventive maintenance with this style of flood detector.
And a side fact is that water itself when pure is not very conductive, you could consider it non-conductive actually, but any time there is anything that adds ions to the water, like dirt, chlorine or salt it becomes conductive. And even if the probe is dry, there may be conductive residue left behind from when it was wet.
Not to say that a dirty probe is your problem, it may be a firmware issue where the sensor is not doing a good job of reflecting the actual charge left in the battery and they need to adjust the calibration factor. Or maybe the sensor is updating the hub more often than it should and transmitting is definitely the fastest way to drain the batteries.
I’d say wait and see how long the battery actually holds up, but being a flood sensor, you may not be inclined to attempt that approach…