App location permissions keep changing from "always" to "while using".

I give the Google Home and SmartThings apps "always" location permission on my iPhone 14 Pro Max. Google Home keeps that setting, but every couple of days SmartThings stops working, and when I check location permissions it has been changed to "while using". Why would my phone keep changing the setting for one app but not the other, and how can I make it stop doing this? This is very aggravating.