Bad print quality on front right side

Hi,

I have a P1P with the self printed Star Trek Borg Cube.
Additionally I added the auxiliary fan.

Since some time I have issues with print quality, but only on certain arenas on the plate.

I now observe it pretty clearly:
I printed 4 times the same parts on one print, 4 of them came out perfectly.
One was bad - tried it two times.

So the quality of the material can’t be the case.
The part on the front of that plate an the right is really poor quality.
But why?
I tried different material, tried calibration but it seems like it is an issue with the position.
Could it be there due to a missing door?
Or too far away from the fan?
But the one behind was good…

The picture shows another try with two pieces only…
One is nice, but the one in the front is terrible.

Someone had the issue before?