There were also several B and C flares, and even one M flare in the day before the X1.5 flare. You can see this series near the limb in the upper right (a clock position of about 2:00) in this daily movie in SDO's AIA 94 Å passband. These flares were also seen in the EVE on SDO and the XRS on GOES-16.
There was no active region associated with the X1.5 flare. A large region of magnetic field that was rotating off the disk is probably the home of the flares.
Solar Cycle 25 is starting to get more interesting!
