Timeout-or-duplicate after 130 seconds

I recently added Turnstile to a form, and I can see in my app’s logs that the request to challenges.cloudflare.com/turnstile/v0/siteverify has taken over 130 seconds to complete, and after that time it has timed out with ‘timeout-or-duplicate’.

What are the circumstances where these requests timeout, and why is it 130 seconds? That seems quite long!