Here is a post on the anime community about it. Basically, there is a bit of a backlash against Mappa by others in the industry right now for setting timelines way too aggressively, forcing tons of overtime on the animators.
This isn’t even a recent problem, Mappa has doing this shit for ages. Taking on way too many projects at once putting way too much pressure on staff for not enough pay. The anime industry is brutal on their staff, and Mappa is probably the worst.