iOS Music app starts automatically while bicycling

When I am bicycling in the middle of the day (not the evening), as I crest a certain hill on a frequented route whatever podcast I have playing on Castro is replaced by the Apple Music app playing where it left off in a piece of classical music. It is very predictable — and annoying. The only way I can stop it is to first open the Music app, then force quit Music by double-clicking and flicking it off. Then, restart Castro playback.

Since it happens only at characteristic time and location, I wonder if it is a Siri location-based event that starts Music. Like other “Based on your current location…” suggestions. This is more than a suggestion; it actually starts Music.

Searching in numerous times and ways I can only find hints for defeating automatic play start-ups having to do with cars, some pretty draconian. There is no bluetooth identity such as a car. (On other occasions the same transition to Music app has started when playing through bluetooth headphones. Recently though, only with plugged in Apple ear pods.) None of the numerous suggestions for defeating autoplay fit this situation or fail.

Does anyone have an idea how to trace this to the root cause, or to prevent it?

Thanks!

This is wired. There is a Siri setting in Settings, where you can control this by app. Check if that helps.