Back when I was at DigitalOcean they were laying off/firing people from the company but not announcing any departures. You'd just go to message someone and their Slack account was deactivated. This was over the course of several weeks. I built a Slack bot to post when accounts got deactivated and learned of some new departures well before those impacted actually did.
https://github.com/eddiezane/no-ghosties