Probably OBS would be your first try, it should be able to do a video capture and is Linux compatible.
Or if you’re willing to set up a VM running Windows you could look into the non-free closed-source stream rippers for 720p/1080p. e.g. RedFox AnyStream, DVDFab StreamFab, etc.
EDIT: Just realized AnyStream also has Linux builds so that could be a non-free closed-source solution.