I agree with the others that this looks like galling, I’ve never seen rust on a Shimano axle, what sort of conditions do you ride in?
I would clean that up with Emery cloth and grease the axle before refitting.
It raises further questions, what BB and frame do you have? Does the chainset require any force to fit / remove? If the chainset requires force to fit it could indicate some parallel misalignment which would explain the axle condition (I wonder about this because the drive side bearing landing looks perfect by comparison).