I'd say it's a poor quality cassette shell that has allowed this to happen. You'll probably have to break the shell apart to fix it, then glue it back together.

Before breaking the shell apart I would take a pen or pencil and turn the lower reel slightly clockwise to loosen the tape and try to pull it gently out of the cassette while doing so. It may get the tape back on the reel without any damage. At least with a clear plastic shell you can see what is happening and avoid making it worse. It's also best done when the dry conditions don't cause static cling or repulsion. During development of the drive mechanism it was a problem with tape damage when starting or stopping wind or rewind but whatever the cause it was solved before production started. See: https://beomicro.wordpress.com/beocord-8000/ and: https://beomicro.wordpress.com/various/