I’ve at least restarted this game 5 times already- it doesn’t save- at all- please 😭
This is a browser-based game, so it saves in your cache / cookies. Some web browsers will auto-clear this at different time lines, this is especially common for mobile users.
There is an option on the desktop to save to disc. This will download a copy of your save file to your desktop that you can then load into the browser whenever. :)