White square halo glitch while using pixel brushes

[Anthonius]

When I use pixel brushes, I see these weird white square halo artefacts / anomalies.  Does anyone know what's causing this?  
Computer: HP Pavillion x360 2-in-one 14" 14m-dw1023dx

Pen: Bamboo Ink

Pen: HP Pen 1MR94AA

(both pens cause this result.)

[Sjaani]

Is the black backing and purple line on the same layer or are they different layers?
Or did you just add a black background to highlight the issue?
It seems to be a very smooth edge on the purple for a pixel brush.

Do you get the same result from any other input device? eg mouse, finger or trackpad

[Olivia5CBF]

i have the EXACT same setup as you and the same PC and Bamboo pen and am encountering the same issue theres one on her shoulder this is my first time using adobe and im dissapointed