Cleaning iTunes Artwork Cache, Please Wait I pressed some keys accidentally on my Mac and then this showed up. No idea what this is. It also doesn't disappear after it finished cleaning the cache.

I have macOS 10.14.6 Mojave.
It is a shortcut from Alfred 3 I was using by accident. It is used for playing music from iTunes.

I also couldn't use Alfred anymore, so I just killed the Alfred process and started it again.