My lines keep shifting upward... – Tayasui Sketches Pro Review

The app used to work fine (albeit the occasional crash here and there), but it’s been very frustrating to draw on it recently due to the fact that the lines I draw keep shifting upwards on their own. I’ll be drawing and a whole chunk of the work increasingly moves upward while becoming more-and-more pixelated. There is also a white and/or black strip across the bottom of my paper every time I start a new piece and I can’t get rid of it. I recently got the newest iPhone 12, so I don’t know if it’s because of my phone or it’s the app itself...Also, I’ve already tried deleting and re-downloading the app—doesn’t fix the problem.
Review by Queenie2n on Tayasui Sketches Pro.