This sounds awful. Software companies have maxed out all the subscription money they can squeeze out of their customers. But sometimes their customers make a profit anyway, an now the tech companies want a share of that too. FYI, Oracle has been doing that for years. The answer to the question of what does it cost is “dunno, how much do you have?”

AI agents can trivially send email. I don’t know what the solution is, other than to disallow submissions from people who already have a good reputation with the project. Even that’s not a good solution, because there really isn’t a way to get a reputation that is open to humans, but can’t be easily gamed by bots.