I doubt it. That's just a room in the Wizard's Tower that you get access to when you have enough hearts with the wizard. I'm thinking the door could just be a visual easter egg, possibly a "fairy door", where the fairies that help your plants come from.
I actually saw that just earlier today too and googled it. The only reason I saw it (I'm on year 6, how have I not noticed it before ) was because I was watching that silhouette of the owl fly across the farm, and it disappeared right at the door. Maybe they're connected somehow? Also, someone posted a video about this (and actually glitched out of the map) and tried to interact with it. He also finds some super cool unfinished secret stuff. It wasn't on the wiki so I was thoroughly confused about it. Also yes I understand I am very late to this party, over a year late actually lol