Good afternoon and thank you for posting on the Final Fantasy XIV Technical Support Forums.

I apologize, but I'm not sure what you are trying to show us. I'm not sure what the circles you made are pointing out. It looks like a gap between two objects, not a white polygon. The geometry of objects will change if you uncheck 'use low detail on distant objects'. This would explain why you are seeing a difference. Do you have a screenshot with it checked and unchecked?

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