My 2023 Prius surprisingly wouldn't start today.

OP. Is the car typically driven infrequently? If yes you may be depleting the battery low enough to damage the 12V through sulfation but not low enough where it won't start the car. Do this enough times and eventually the sulfation and battery depletion will be enough where the almost dead 12v can't start the car.
I monitor the 12V batteries in both of my cars with an inexpensive BM2 Bluetooth monitor. When a battery get's low enough where it's in danger of being damaged I charge it up with a smart maintainer/charger. Not only does it charge the battery it also reverses the effect of sulfation ergo keeps the battery healthy.

 

My 20 Prime is back to not charging properly as the weather warmed. Charging the 12 v all night again. Not that it wouldn’t start the car, but it was at 70% and the voltage lower on the battery monitor, forget what don’t pay that much attention to voltage anymore unless it drops very low. Have other things in life to attend to, monitor tells me what I need to do fast.

 

Do you have a vendor list for the affected batteries?

 

It has nothing to do with the battery itself. The vendor has always been the same, which is GS Yuasa.

The problem is caused by the buggy 12-V BMS (battery management system) that likes to keep the 12-V battery at 75% SOC for fuel economy (by lowering the DC–DC-converter voltage) instead of the traditional 100% that favors battery longevity. Along with some bugs in the software, this could cause the battery SOC to drop over time and discharge and/or damage the battery.

1. Most owners will be fine as long as the car sees regular long trips.
2. Another issue is with cars that already come with a low 12-V-battery SOC from the dealer when purchased due to improper maintenance by the dealer. Those batteries are usually damaged and need to be replaced.
3. If the car does not see regular long trips, you need to hook up a battery maintainer, as the battery loses up to about 3% SOC a day, and short trips will not make up for that.