I'm experiencing the same problem. Aside from that, I would prefer a dark environment over a light one. Maybe you could include a dark theme? At the moment, I don't really see the benefits of the p5.js editor over other code editors like Visual Studio Code...

The editor is so useful for teaching students and having a way to set up a sketch's dependent files very quickly. Saves so much drama dealing with paths in a classroom.

Just a note that this bug affects the example code included with the editor. I ran into it a minute or so into using the editor for the first time, after tweaking a value in the "Array 2d" example. I ran it, noticed it was slow and refreshed to see if that was normal (it was, I had changed 'spacer' to 1), then closed the browser and discovered I had to close and reopen the file (but not the whole application, I still had another window open and it appears to be working OK) to be able to run it again. Just thought a little more information might be helpful.