This is anecdotal obviously, but we recently moved to a new house a bit further away from the city (Western Europe), and we definitely noticed that the flies are very slow and generally apathetic / lacking self-preservation instinct.

Many times they land on a table and you can nudge them and they don't even fly away. We attributed it to the recent change in location, like maybe the flies here are stupid or since we have many more lizards maybe there is weird selection bias.

There is also virtually no mosquitoes even though we are near a lake and when we used to come here a few decades ago they were everywhere, it was a impossible to stay outside without repellent.