In a live match, my opponent played Hydroponics Architect. (When this creature attacks, a random land in your library perpetually gains “when this enters, draw a card” and becomes an Island). I played a Blood Moon (All non-basic lands are mountains). My opponent got several Architect triggers, both before and after Blood Moon resolved. When they played the lands that had been affected by the Architect triggers, they were still Islands and still drew my opponent cards. Based on my understanding of the rules, the non-basic lands they were playing should have had no abilities when they entered, and should not have remained Islands.

As a separate issue, there should be official rules for Arena-only mechanics like Perpetual, so that people can understand whether an interaction like this is intentional or a bug.