Hi softballjohn,
Welcome to the Apple Community where some of us do our best to help each other.
Seems exporting files as MP3 files loses a lot of clarity, but makes files that are lower in Gb / Kb.
Exporting from GarageBand as .aiff or .wav produces better sound, at the cost of higher Gb / Kb.
Apple has a support page with a way to export quality files from GarageBand:
https://support.apple.com/en-au/guide/garageband/gbnd7cbf5ed9/mac
There is also an online User Guide, for GarageBand (with a Table of Contents) that can be very useful:
https://support.apple.com/en-au/guide/garageband/welcome/mac
Best regards :)