Thanks for playing and reporting the issue! Another player reported a similar case. I suspect it's a result of logic meant to address other bugs I was seeing during development (which resets the drawing if `delta` is too high), but I'm not sure yet. Changing tabs can causes the issue, too. I'm sad you didn't get to see the final drawing, but I've included the spoiler below:
https://editor.p5js.org/jcponce/full/x-Jt7k2fc
I forgot that comments on jam submission pages don't get collapsed, so for those that haven't played yet, don't click the link.