Obviously poor prep as it was originally epoxied on from factory. From photo of washer, it doesn't have sufficient epoxy behind it. You should see it oozing out at edges, a sign that all gaps and voids between washer and dropout has been filled.

I've done this repair on numerous frames, starting with aluminium frames back in '80s. On some frames, washer have pins that goes through dropout and are welded to washer on other side.