There wasn't any "slowdown" when I made the comment you are referring to. Development for RD started in November 2022, which means Chapters 16, 17, 18, and 19 of CD were all released alongside active development for RD.Because that's why you don't start a second project and tell all the supporters that you've built up due to the original project there will be no slow down on said original project's release schedule or its priority level, which is exactly wtf ionDivvy did.
CD later faced difficulties getting approved on Steam, which had a significant impact on its development speed.
People being weird about the game - plus the drama during the Chapter 19 release - also did not help because it took away some of the joy and momentum. To be honest, it's kind of bizarre to me how a cute slice-of-life porn game (and a free one at that) managed to attract such miserable and frankly unhinged people. Thankfully, 99% of CD players aren't like this and have been much more supportive.