okay that marvus clip actually gave me a good idea of what's happening
basically the game likes to rewind to the most recent "label" -- there's a label at the start of every route, which is why the game rewound there if there's not any closer one. the trollian label exists, the "blueblood car" label exists, etc.
i didnt code the save file system so i dont really know how to help... "perhaps the script changed in an incompatible way" really is what's going on, i think.
what's definitely interesting is the "unseen text" resetting. are you redownloading it each time, or using the itch app to update?
i'll ask around in the renpy discord for help pretty soon o7