lip apparently contributed to a lot of ingame content (events, characters like the mushroom women and ophelia, etc.), but no one besides lip and mofu knew until recently. lip says she wasn't credited because mofu wanted to sell the game as his own creation. mofu says he didn't credit lip because she herself requested not to be credited.
but, as you can see, people don't care if mofu doesn't design every character. he does the art and programming which is what matters to most people. hell, the two characters on the roadmap aren't even his but, again, no one cares. we're only here for a fun futa game.
lip also felt like mofu was going to rush the game so he can sell it for some quick money. they weren't able to discuss and settle things privately, so lip started pleading with him publicly here on itch. we don't even know if mofu really planned on rushing the game or releasing it incomplete just to sell it, but she felt angry about her characters being used like that and not being credited, even though mofu said she didn't want to be credited.
lip then got even angrier on the subscribestar poll (since it was regarding her character ophelia) and got fed up with trying to get mofu to discuss things in private. in one of her comments she said "I've been creating content for this game for more than 2 years, so if you're going to try to sell my work as yours, you will need to remove all of it."
this led to mofu removing lip's characters from the character sheet on this page, as well as the roadmap.
whenever the next update drops, we'll see what else is removed and what direction the game will be going in from now on. but it will continue.