Preparser doesn't fetch embedded cover art from FLAC files until after the file is played
Arch Linux, VLC version 3.0.21 from the official Arch repo
When adding a FLAC file with embedded cover art to the VLC playlist or media library, the art isn't automatically fetched, so it just shows up as a cone icon.
It isn't until after you play the FLAC file that the cover art appears.
This issue is only with FLAC files, not other formats such as MP3. I can't attach a sample because I don't have any that are less than 10 MB, but any FLAC from Bandcamp should reproduce this bug.