The strange part: In my experience, this is easier at a single-tenant/single-customer on-prem system than in AWS / a multi-tenant hosting.

On-Prem, the operations team can announce: Hey, System XYZ won't be available Saturday Morning in two weeks due to an upgrade. Then you shutdown the entire thing, change the column name and start it back up on a new version. I've had a few chats with system responsible people at customers even for very large customer support organizations - to them, a well coordinated and controlled downtime is something they can just work around and it might even be preferable over a more complex, less controlled maintenance without downtime.

In our own hosting, the more complex migration procedure would be easier to coordinate and execute though, than coordinating such a downtime with a lot of customers.