The PKK is a Communist terrorist group and was so long before Turkey went islamist. They terrorized their fellow Turkish Kurds into appearing to support their goal of a Communist Kurdish state in Turkish Kurdistan.
Soviet client state Syria was a big supporter of the PKK back in the day. That might have something to do with Turkish hostility to Assad Syria. But no doubt whatsoever that Erdogan is an enemy.
I realize PKK had strong soviet influence in ideology when it was formed in 1978. They’ve moved away from that since 1999 & have since moved towards Kurdish Nationalism and since 2005 their leader publicly stated that their reformed stance espouses a ‘democractic confederalism’. There was a peace process with Turkey in 2012-13. But since ISIS and Erdogan’s continuous refusal to help the Kurds, that fragile peace process has fallen apart. To continue to alienate PKK & their Syrian affiliate YPG will only add fuel to fire. This situation involves the actions 2 parties, Turkey and the Kurds, not just PKK.