DaVinci Resolve has a native Linux version, with the caveat that it can't import mp4 files (have to convert them to another format beforehand with a tool like ffmpeg.) You also may have to do some tinkering based on your hardware - Arch Wiki has a good compatibility table, though the Debian packages will probably not match what Arch Wiki has listed, and you'll need to use the installer from the Resolve website since I don't think Debian has it in their repos.

If you're looking for something free & open source, Kdenlive is also a great option, though it doesn't have nearly as much functionality as its more professional-grade counterparts.