The problem here is "open source" is seen as free support and working for "the community" for free and since the code is out there, no-one needs to pay the maintainers. (which is false)
Some mention GitHub sponsors as the solution, however it is a power-law system and benefits the very early participants or already famous developers to make a meaningful amount of income. But it is now at its late stage for everyone else. In some cases, some maintainers on sponsors get attacked / cancelled over a disagreement and that is the end.
It is completely thankless and unsustainable. $5 donations do not work either.
Now with AI, unless you are at a company that can afford it, there is little reason for human developer(s) to be working in open source and relying on $5 "sponsors" since AI agents are used to replace the need of paying for support for the developer.
What worked 20 years ago for paying for human support, now does not work today unless you do not mind about willing to work for free and spend some tokens. If you don't someone else will with an agent.
Not even Richard Stallman or the FSF makes money on this, nor do they have a solution in 2026 as it is unenforceable. But one thing that Stallman, Torvalds and other famous developers have is influence and that is what pays their bills.