Since the AHM website is not available to the public anymore, I can't browse fleet information pretty easily on the web but one of my domestic flights in the fall now have an A321 Y215 configuration, which is quite odd since TK doesn't have such aircraft at that configuration. The aircraft code is filed as "3HD" which HD likely means "High Density" and I am not sure if these would be new or secondhand aircraft joining the fleet or they would reconfigure some of the old aircraft to that configuration.

This is on a TK operated domestic route out of Istanbul Airport ( not AnadoluJet ) where no Business Class is offered.