print is tilted only in bottom layers

[termatzor 0]

I have built a little 3D corner object to test the alignment of my UMO. Interestingly, the print is strongly tilted x-direction in the bottom layers (3mm) only, the y-direction looks fine. I have already strongly tightened the pulleys as recommended in older posts. This effect appeared from one day of happy printing to the other...

I am curious to learn your interpretation why this tilt is so much z-dependent.

Thank you,

Mattias

[tommyph1208 55]

Does this happen with other prints as well?

How does your layer view for this print look in Cura?