This really does not sound healthy. The game is released, for a certain amount of money. If people don’t like what they get for their money, they simply should not buy it.
But by now gamers have been so trained to expect to endless content treadmills and all their ilk like mtx and battle passes that publishers/developers get egged on if they don’t work on their game 24/7 and forever.
I appreciate the solo developer, and that they are doing most everything else right, but he opened this can of worms because he sold early access. He could have chosen to wait until the game was finished to release it, but I imagine wanted the money up front from early access to help finance the development.
If you release unfinished, you open yourself up to your customers wanting it finished, and also wanting a say in how it gets developed. I’m not saying he doesn’t have a right to sell via early access, but he brought this on himself.