My son got an email saying he needed to migrate our Mojang account to an MS account and he clicked through like the email said. Problem was the Microsoft account he migrated to already had a Minecraft purchase. Now I essentially lost a copy of the game because we technically have two Minecraft accounts with the same email. We can only log into one of them.
I contact MS with the best link I could find but it was not actually linking me up to a MS employee, but cycled me through four different "experts", each of which I had to re-explain the issue, and each said they didn't know how to help me before bouncing me to another expert. It was a terrible experience and still unresolved.