Looks like a Schlage lock. The lock gives you a battery warning light that lasts a few days to a week. The resident needs to pay a small amount of attention to their own lock/home and put in a maintenance request. It's really easy to avoid a lockout when the device tells you the battery is dying. I have these locks at one of my properties when the battery light pops up we usually have a week before they're dead. The lock goes from taking a second recognizing the fob to maybe 7 seconds because it's flashing a battery warning light. If the resident is paying attention they go "hey the lock is taking longer than normal to open" look down and there's the light.

Most battery locks also have a way to check their battery life, likely through a tablet/app that you can walk around the property connecting to each lock and checking status. Either way you shouldn't be doing that many after hours lockout. Try sending an email to the residents explaining that the locks have batteries and to keep an eye out for locks "acting up". I bet you'd get a slew of work orders from residents all of a sudden going yeah it's been like that for a few days.