I just went from the 4.35 or something update to the 1.0 update. Suddenly I'm not getting any of the birthed canal parasites, I get the werms and the chokers but not the canal.
I went to their Patreon, and it went from 4.37b down to 1.0 on July second.
There is no public post explaining why it was rolled back, and I'm not pledging just so I can read why the game's progressed was regressed by so much. However, I do plan to pledge (in the future as I'm broke right now) in order to access the 4.37b if it's still available when I can afford to pledge.
It's possible they had to switch engines, and going back to the first release was the easiest way to convert it.