As a software house, we have many teams on different projects. One project was due to a Thursday, and the PM asked the team 1 week before if they could work over the weekend since there's a lot of things to do.

On the Friday before, one of the devs showed up a bit later than usual (around 10am), but ok...

After lunch he asked to talk to HR and also the boss. They talked for around 2h, then he started to say "goodbye and good luck" for everyone.

The project was on fire and he just... leave.

On the next 2 months another 4 people leave the company. All from the same team/project (but not with a big surprise like him).

Apparently, the team was constantly complaining to PM and boss about unrealistic deadlines and constant requirements changes, but they didn't did anything about it. Just when more than half this team had left the company they started to rethink this actions to this project and the others on the company.