Saw this on tumblr and don’t remember having seen it here as a potential reason for Tink’s banishment, but Tink’s potential banishment is a popular theory, so…
Tinker Bell is the one who helped Regina preserve Daniel’s body. She was banished by Blue for that.
I have wondered before how Regina managed to preserve him, because she wasn’t into magic at the time he died, and if a body is gonna be preserved, it’s gotta be done ASAP. So this little theory intrigues me.