Ender 3 strange vertical line in print

Hi guys,perhaps you could help me with this issue.On my prints I see some very slight vertical issues/wobbles.What could be the issue here?It are multiple straight vertical lines also they have the same distance between them...Is there some belt issues with X or Y axis? Or what could be the issue?Using Marlin 2.0.5 and Ender 3 Pro with silent board.Attachment 14531Attachment 14532Attachment 14533PS: I had some layer shifts before but that was more a horizontal issue. This I fixed by tightening the hotend. So now this works great.