Cliffnotes version, this game stopped seeing serious development after 2018. The game's updates became far less frequent with one update in late 2019, another in mid 2021, and the "final version" only arriving recently.
Some of the cut content is blamed on Patreon forcing their ToS on the game, because Patreon itself were contacted by disgruntled fans around the 2021 update, basically non-consensual stuff being rewritten or cut, and rewriting character ages as two examples.
The original scope of the game was cut as well, with the original planned endings that were teased in previous version, the harem and pregnancy routes, "coming as dlc" because you can never stop the milking.
Imo, this game isn't finished, they are just calling what they have the finished version, and this supposed dlc is another carrot on a stick that could bear fruit in 2 more years if anyone who chooses to wait it out again.