You do you, but a little professionalism goes a long way. Maybe that manager moves to another org that you want to apply at, and they reject you because of how you acted the last time. Or maybe they just tell someone at the new org how you left.
Doing this has zero benefits to you, sending an email takes almost zero effort and might have some benefit for you. The rational thing is to send the email.
Surely this doesn’t require two posts. Here’s the other one.
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