I have an app deployed on fra (main region) and on gru.
I happen to be in Brasil right now and I was testing a couple of things and I noticed that the GET request are never being routed to gru, they go straight to fra server. ok, “never” might be too strong, I see that every like 70th request goes to gru (ballpark guess).
Such is the wild world of Anycast that it could either be the ISP or the infrastructure providers Fly uses that could be causing this.
If it is any solace, I routinely see traffic to Cloudflare’s network (presumably a much bigger Anycast deployment) from Mumbai routinely routed to Amsterdam, Paris, and London instead (unsurprisingly, happens with Fly Anycast, too: Global anycast routed to AMS).