This is why buying from Steam directly (or Steam keys from legit stores) is usually your best bet for Linux and Steam Deck. This is of course a good reminder that the Epic Store doesn't support Linux and the Steam Deck in any way, so they can break anything whenever they like and it's up to the people working on third-party stuff like Legendary and Heroic to figure it all out for us. Giving it a test myself with the new hotfix and yup - it works again. According to the source, this trick will not work on these below-listed games. You need to first navigate to the AppData folder in your Local Disk C, the path for which should be something along the lines of Computer> Local Disc (C:)> Users> your username> AppData> Local> EpicGamesLauncher> Saved> Config> Windows. With Heroic version '2.4.2 HOTFIX #2' you should be good to go on logging in and downloading games once again. Just open the game files, locate the (game).exe file and create a shortcut in the same folder, Open the properties of the shortcut, and in the target field add ‘-EpicPortal’ at the end. Legendary, the name of the kit that the Heroic Games Launcher is built upon for its Epic Store integration was updated and so the Heroic Games Launcher has pulled the latest version in.
Recently it seems something changed over on the Epic Games Store and so third-party programs trying to login like the Heroic Games Launcher would fail.