As in software that’s licensed under a open source copyleft license, but costs money to run that’s beyond an optional request for a donation. I can see this happening with libre hardware since it still costs money to manufacture even if the design is free, but with software, wouldn’t someone immediately fork the project to remove the payment requirement?
From what I remember, the FSF has nothing against selling your product, it’s the source code which has to be available.
In other words, you can sell a free software, yet users can pool together the resources to buy your product and install it multiple times, or they can even just get the source and compile it, and even redistribute it