The Meeting Migration Service has now been updated to support migrating from SfB to Teams, when you change a users upgrade mode to Teams only their existing meetings will be converted auto-magically. Check out a demo of this in my latest video ….
@Steven Collier. Do you know if this works if you're on-prem exchange? I started as a SfB onprem user that migrated to SfB online. I had to use the MMT since my mailboxes are on-prem. But doesnt look like the meetings convert when i migrate to Teams. I see similar when I migrate from OnPrem SfB to Teams. still need to use MMT but it converts the appointments to SfB meetings. Maybe they will do away with this when they sunset SfB online?