Apple has released a security update for the music software Garage Band.
The update raises the version number to GarageBand 10.4.3, but is only available for macOS Big Sur. If the software runs on other supported operating system versions, the problem does not seem to occur.
Apple’s support document is currently silent on exactly what the bug is. If you use GarageBand under macOS Big Sur, you should update the program at the next opportunity.