I was removed from the beta as well.
I don't believe that not submitting/submitting any feedback for the
beta would be a reason to be removed. Since I for one, like many
others who have been removed, have been submitting feedback quite
consistently. Most recently on the latest release; 5.1 - 236
Maybe it's because the current focus of development is for Flicktype
for Apple Watch, and so, only the testers who own an Apple Watch are
currently still getting the betas?
Just speculation though...So, it would be great if Kosta or Ashley can
provide some clarification regarding this.