[yoloClin]

I'm more curious about how DB rollbacks occur in situations where a PR changes DB and is then reverted.

[aledalgrande]

It would be a good practice to first make a DB change alone, which is compatible with both and new code, so you don't need rollbacks. Then separately deploy a code change.

Edit: also suggested by Martin Fowler https://www.martinfowler.com/bliki/BlueGreenDeployment.html