I had a similar experience with a side project. I used an .app tld since it was available and, hey, it seemed kind of cool. Then I told my friends and they were totally confused- “your apps not on the App Store?”
I own a .app domain and in naming a folder on my Mac that I lost the ability to open the folder in Finder. Cracked me up and outside of the terminal I could find no solution.
This is good to note. I remember I was trying to hit return to rename it and that would just open it. I was probably tired because I felt so flabbergasted! It looks like you can rename from right click too. Not sure how I missed that
Ugh. Lesson learned.