This was already the case for 18.7.7. However, after turning automatic updates off in 18.7.7, after updating to 18.7.8 it remained off (reproducibly on several devices I updated). Maybe there is a one-time flag that is set so that after turning off automatic updates after having been turned on automatically, they aren't automatically turned on again on subsequent updates.

Huh, my experience was the opposite. I don't think Apple undid my setting with iOS 18.7.7, but they did with iOS 18.7.8.