Please help! Annoying border on objects.

[Judi26158882eklk]

I have a problem, that I really don't know how to solve, or what I did to make it happen... 😞 When I use the shape builder tool, or simply paste one shape on top of another, there's a line coming out from the shape bellow regardless if they are the same or are perfectly aligned. I don't know if I'm explaining it correctly, but it's really annoying 😞 I've attached a picture, thank you all in advance.

[Barbara Ash]

Is there a stroke applied to the shape?

[Judi26158882eklk]

No stroke at all 😞

[Jacob Bugge]

Judi,

What happens if you holde Ctrl/Cmd and press E, to toggle between GPU and CPU?

[Monika Gause]

Please show us how this looks in the Layers panel

Please select the elements one by one and show us what the Appearance panel shows.

[Ton Frederiks]

What happens if you uncheck Anti-aliased Artwork in Preferences > General and use View >  View Using CPU?