From the comments, there is some confusion about why did i attach my personal email to a company account. That was not the case, let me clarify it. I created my personal account long before Trello was acquired by Atlassian. It did not have any SSO at that point and the login was with username and password. At some point, while working on a side project and to share it with a teammate, I attached a secondary email to my account and created few boards under it. This email was my companies email @company.com

The multiple account login used to work the same way it works for github now. The boards were very clearly labeled under the email/username they were created and clearly had the ownership well defined. As soon as I left the company and my email was disabled, all the boards under that email disappeared from my account. This was expected and kept using my primary email (i always used to login with my username) and completely forgot about an attached secondary email (which anyways is now deactivated). Fast forward 5 years with tons of personal boards under this account, one morning it stopped working without any notification (yes i revised my spam to be sure about it) with all my data gone.