Yeah fam, they FLEW through it. Like
@T-K-G said, it's almost a highlight reel of the events. Not only did they condense a shytload of chapters, but SIU used to write long bits of lore at the end of each chapter. The anime could have expanded the world like crazy, but my theory is that they were scared to lose viewers in the downtime between action sets...but the downtime was loaded with character development, plotting, and betrayals...a lot of good shyt got dropped.
But the good news is I genuinely think this playlist is all you need to catch up. These dudes do a good job breaking down what you missed from each episode.