Which license for closed-source application?

I have a closed-source application I’d like to publish to Flathub, but I’m a little unsure about the license field. There is no license for the application, and it’s really only closed-source to mitigate shady forks. Reading the publishing guidelines, it suggests that proprietary applications need to link to legal text… but there is no legal text for my application. I can certainly create a page with some thoughts an opinions on what people should do with it, but I’m not sure that’s really in the spirit of this metadata field. Any recommendations on how to proceed?