I don't know if this will answer your question, but I had just come across this little paragraph a few days ago and thought I'd share it with you:
"The rate limit for third-party calendar applications and services is 80 requests per minute per IP. If you get a 429 error (Calendar sync too frequently), you’re hitting the rate limit and you should slow down your requests, spread them more evenly across the hour, or retry the request the next hour."
It's at https://www.airbnb.com/help/article/1295/what-are-airbnb-s-calendar-sync-rate-limits
I don't understand a word of it, but maybe you will! 🙂