https://www.reddit.com/r/TheSilphRoad/comments/ak2el6/no_psyduck_in_long_island_new_york/
多分これ

Some of you may be aware that Long Island is currently under the influence of what residents have been calling a “meganest”.
The entire area behaves like a nest due to an edit somebody made to open street maps many months ago. Currently it is Chinchou.
They are spawning all over as is typical for a nest.
What’s not typical is the fact that the meganest effectively blocks event spawns such as witch and santa hat Pikachu.
Right now there are zero Psyduck spawns on Long Island.
This is a warning to players: do not come here for Psyduck- you won’t find them.

The POGO community of Long Island has been waiting for this to be fixed since before spring 2018 and collectively have sent hundreds of support tickets.
We have no indication from Niantic that they have any intention of fixing this.
Despite the bombardment of support tickets we don’t even know if they truly understand the issue.
Please give this post some visibility so people know what’s going on here. Thank you fellow trainers.