Yes - this smells very much like FC.
With the retirement of Aero last Sunday all the AY HEL-TLL flights are now operated by FC, apart from AY107/108 on Sundays, which is still a mainline Airbus (must be due to some lucrative cargo contract).
I wonder when FC will start operating to RIX and potentially VNO as well - then we will see some nice combined HEL-TLL-RIX-HEL circle flights to patch up cancellations like they often do on the lightly loaded domestics...