flutter/packages#8629 will fix the preview rotation when the camera plugin is being used without a locked capture orientation. However, when the capture orientation is locked, it may impact the orientation of camera captures and video recording, so the CameraPreview widget will be rotated according to it instead of the device orientation as the aforementioned PR assumes, see source.

flutter/packages#8629 should be followed up with a fix to modify the preview rotation calculation to account for that CameraPreview rotation regardless of whether or not the capture orientation is locked.