

I would guess it’s a timing issue; since the layers on the front part take longer the back part has longer to cool and shrink in relation to other layers. Maybe a draft is increasing this effect - do you print in an enclosure? If yes, maybe a setting a minimal layer time might help - that way all layers have an equal amount of cooling time.

It’s difficult to tell height and things lining up in the photo - if it’s all over the part it might also be feeding issues or ringing. If it’s ringing check how sturdy the platform your printer sits on is or decrease printing speed. What machine are you using with what settings?