The changelogs detail all the new content.
Viewing post in Corrupted Kingdoms (NSFW 18+) comments
This does bring a point...
Game could use something like "ingame changelogs" or some sort of tracker for side content.
I mean, any regular player that just jumps blindly into updates wouldn't have much of a clue what's new, all the leads and girls cards have been stuck on the "no more content" thing for months.