The ex-guy was apparently chatting with a presenter whom I work closely with when I joined the session. I heard his voice. He said a single word that I couldn't make out. I have a feeling that he saw my name and reacted by saying some word before he stopped talking.
I hadn't heard his voice since June 2019. It was weird.
I was okay. I am okay. As long as we don't interact, I'm fine.
We still work for the same employer. It helps that we aren't in the office and we are in different departments. Otherwise, it would be awkward.