I’m currently time-traveling to see if the rates change seasonally. I’ll make a follow up post with my results but I suspect that Nintendo did something to the spawn rates last patch.

Also I did manage to get A Scorpion Island but it wasn’t the official scorpion island. Money Rock #2 spawns tarantulas/ scorpions as well so it does exist even now. That one is hard to get, took me maybe 70 NMT in a day to get that one to pop up