> Long slow bend

That’s probably it.

If I were designing a wiper fluid warning, I would use some sort of fluid level sensor and I would denounce it aggressively: the indicator would only light up if the sensor detected a low level for more than a couple seconds. That way traffic circles, bumps, etc would not cause many false positives. I might even couple it to some kind of acceleration sensor so a warning would not turn on during or shortly after any heavy vibration or acceleration.

A long slow bend would cause a prolonged, steady centrifugal force and/or sideways acceleration due to a banked road, which would defeat these mechanisms.