If you want to avoid this, then you'll have to design your level to ensure people can't have the umbrella open, either before or after you've taken away the power.
For instance, Make a jump that is high enough to be only reached without the umbrella and either set the shift before or right after that part (can be a teleporter you must reach)
If you do a test after the shift, make sure people can kill themselves somehow, and put a save right before that shift, so people have a chance to get there properly.
But yeah, a cutscene is better.