I'm not sure if this is intended as a breaking change (although I don't see it in the migration guide) or if it's a bug, but the interpretation of the position property for a vertical line has changed in chartjs-plugin-annotation 2.0.0.

In 1.x, position: 'start' meant the top of the line, and position: 'end' meant the bottom of the line. (This feels more intuitive to me.)

In 2.x, position: 'start' means the bottom of the line, and position: 'start'` means the top of the line.

Demo: https://codesandbox.io/s/chartjs-annotation-label-position-th2kcr?file=/src/index.js (You can change the version of the plugin in the "Dependencies" section in the left sidebar to demonstrate.)