Maybe this all looks like networking issue. In fact, Stripe or Algolia clients would, at the end, just call an URL too.
I had problem with upload too, but it might have been related to input timeout, which was 30s and was raised to 60s as per this thread: Realm functions 30s input timeout
Now back to us, I also tested a Ream App deployed Global vs a Local, just in case. And no difference. The Algolia saveObject just reaches “execution time limit exceeded” in both apps.
Looks like I should give up Realm Functions.