About the use of the loops from GarageBand in own tracks

Apple is granting you the right to use the loops even in commercial projects. You can publish the songs with the Apple loops in social media freely. But the social media may still prevent you from using them online, if they see, that someone else has used the same loops and claims the copyright.

See: Using royalty-free loops in GarageBand with commercial work - Apple Support

Using royalty-free loops in GarageBand with commercial work

Learn about the usage of royalty-free loops in GarageBand on commercial songs, multimedia presentations, videos, and animations.

The GarageBand software license agreement says:

"GarageBand Software. You may use the Apple and third party audio loop content (Audio Content), contained in or otherwise included with the Apple Software, on a royalty-free basis, to create your own original music compositions or audio projects. You may broadcast and/or distribute your own music compositions or audio projects that were created using the Audio Content, however, individual audio loops may not be commercially or otherwise distributed on a standalone basis, nor may they be repackaged in whole or in part as audio samples, sound effects or music beds."

So don't worry, you can make commercial music with GarageBand, you just can't distribute the loops as loops.