"I can confirm, that under Linux Mint 20.1 Cinnamon (64-bit), I was able to write UEFI-compatible USB stick. Wrote also Linux Mint 20.1 ISO-files (Cinnamon, MATE, XFCE)."
"At https://github.com/mifi/lossless-cut/releases there is already several months out multiple new versions: currently 3.23.8 but in Flatpak is still old 3.22.3. Looks like even under Snap is newest version available. Have to download AppImage therefore as I don't want to install Snap under Linux Mint."