Firealpaca official backup instructions for brushes: https://firealpaca.net/material/easy-backup/ (Surprising recent Firealpaca ad screen link)
From their website:
"Starting from Ver. 2.13.17, backup and data restoration of “Brushes”, “Colors”, ‘Gradients’, and “Shortcut Settings” has become easier!"
Steps to backup and export your personalized Firealpaca data (brushes, colors, gradients and shortcut settings on your disk:
Open Help menu > click "Export Settins"
A new pop-up dialogue window "Do you want to back up your brushes, colors, gradients and shortcut settings?" > OK
Old way to back up all your personalized settings, brushes and materials (also it has been anofficial Firealpaca HUB tutorial for a while now):
How to transfer setting to another computer? https://hub.firealpaca.net/how-to-transfer-setting-to-another-computer/
Open Help Menu > click "Open Confiq Folder"
New window pops up. Copy-Paste everything to another disk, USB drive, zip it, upload it etc to back it up.