The only rule that might drop the set point of cool lower would be the Smart Humidity rule, but it looks like that is off.
The thermostats are likely running old or default schedule data if you are 100% sure no one is manually setting the temperature.
The first step I would suggest is to factory reset the thermostat. Then delete and relearn the thermostat into the panel. It looks like thermostat 2 is the one doing this, based on recent history.
Then, if you want to use schedules, I would try to alternate the temp in the schedule. The schedule is designed to change the temperature at specific intervals, and if the temperature would not otherwise change the rule won’t fire based on previous instruction from ADC. That means that setting the same temp for all intervals in the schedule won’t behave as expected.
It won’t set wrong temps, but it may not be saving properly and overwriting the old schedule. If you want to use schedules, try changing it to 77-78-77 or something similar as a test to make sure it is automatically switching properly.