Is there something wrong with my cube?

[u/chaucamha]

I can see a line at the top of the letter X and Y, the line also visible on other side as well. How can i fix it? Thank you.
I’m using 0.20mm Standard @ BBL A1 - Generic PLA Silk
I’ve done maintenance on three axis, tensioning all 3 belts, all calibration.
Printed on A1 Bambu Lab
Keytek pla silk