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?
Most open source apps that have a cost I’ve run across usually have the option of building it yourself for free. But if you want prepackaged with support you pay.