When an exercise first shows up, only the "skip" button appears in the bottom bar. Once you make an action (click, start writing, etc) the bar does a little "jump" where it slides down and slides back up, now including the option to "submit". This is somewhat distracting as the bar keeps jumping up and down in your peripheral vision.

Since the skip/submit bar is already there, I would suggest for it to be static and to instead have a greyed out "submit" option which changes color once you make an action.