My prints are bowing after a few hours.

I have had my Anycubic Kobra for a year and it’s had decent use with no real problems. Over the last few weeks I have been having this problem where prints begin to bow at the edges after a few hours. I watch the first later go down and everything seems adhered properly until after about the 4 hour mark where it will start to bow and eventually come away from the base. I’m using Geeetech transparent PETG.

Settings E0 temp: 220 Bed temp: 60 Fan: 100% Z-offset: -1.55

Is this a user error or something deep lying about my printer?