Happened a while ago at a previous employer, just reminded by a recent story.

I often presented my desktop in working sessions, and due to "presentation mode" - a form of "do not disturb" - I would not be notified of new chat messages.

There were a couple situations where my manager and a couple others, who rarely sent messages, we're unable to reach me for something urgent.

Since there was a setting to allow messages from some users to bypass "do not disturb", this seemed like the perfect use case, so I enabled this for my manager and a couple others. That was the FU. It actually helped me out a few times, and caused no issues... until it did.

I had a call to discuss something privately with my manager, agreed on next steps, and was told not to tell anyone else until they could discuss with a couple others. I'm big on transparency and this didn't sit right with me, but it wasn't my company so, "okay."

During my next call I was sharing my screen and demoing something to several coworkers when I receive a message from my manager. Because I had set it to allow him to bypass "do not disturb" there is a pop-up notification that says essentially: "Remember to send HR your resignation letter."

I instinctively closed it but heard a collective gasp from members of my audience. I said, "well, that happened.." as someone asked, "what? What just happened?" and another person tried to say words to explain but fell short due to shock as the question was repeated. Clearly some people knew, so the only way to reduce the disclosure was to explain and tell them my manager had said not to tell. So obviously they told everyone, but that meant fewer people I had to tell which was ok. I miss working with most of them and stay in touch.

TL;DR - Manager told me not to share my pending resignation, and in less than an hour they accidentally shared it instead .. because of my chat preference.