We believe this is from a bad service worker so although a hard refresh should clear it, to remove the problem we advise also unregistering service workers. To do that you can:
1. Open the dev console
2. Go to Application
3. Select Storage
4. Make sure 'Unregister service workers' is selected
5. Click 'Clear site data' and then refreshing the screen.
I made a little video to help with that: https://www.loom.com/share/dafeab2bab59436b8f724a420820a3f9