For some reason the image did not stay when I posted the question.
For the record, I was talking about the general decker tools in the initial post, by activating the toolbar and drawing on a blank card, but it seems to be happening in both decker and wigglypaint.
I opened wigglypaint in the actual decker application to test if it had the same problem, and indeed encountered this issue again. The html version does not seem to have the issue, but it is overall slower which makes sense. But there is no weird line jumping. It's a little hard to tell using the regular line tools, but using a marker I could see this really weird delay very clearly when I tried to draw a circle:
If this image doesn't load, here's a link: https://imgur.com/a/4p8VxiS
My tablet runs on windows, it's basically just a touchscreen computer. It's not an ipad or anything. I don't think I've encountered this issue before in other programs, but my memory is unreliable. Either way, this is currently the only program I'm experiencing this issue with.