Thermostat heating beyond threshold

I’ve installed two thermostats in my house, and everything has been working well enough except for one hiccup. Occasionally the thermostat will continue heating a zone well beyond its programmed threshold. I’ve woken up sweating in the middle of the night for the last week because hot air continues to blast, which has been taxing, to say the least.

I checked the app last night, and it showed that the threshold was set to 66, and the thermostat was reading 67:

It continued to run for another 10 minutes and finished heating to 70 degrees:

I confirmed the downstairs thermostat did not have the heat turned on, and air was not blowing in that zone, so it was just the upstairs.

Any idea why the thermostat is turning on the heat when it’s temperature is above the heating threshold? And why it continues to heat for so long well beyond that threshold?