When i create files for mp3 files on my CIRCUITPY drive and make changes the drive fills up faster than it should. When I inspect the drive on a PC I see lots of hidden files.
What I am seeing are macOS metadata files. These files are often as big as the original file. Which results in halving my drive space.
._filename.mp3._filename.wav._anything.DS_Store
To clean them off I use this set of commands in the terminal.
find /Volumes/CIRCUITPY -name '._*' -delete find /Volumes/CIRCUITPY -name '.DS_Store' -delete