From the ad copy...
...as seen in picture 8 the rear pannier eyelet has shorn off the main frame. There are frame builders that can braze this back on for you, but I don't have the skillset to do so myself....
Ouch, that left an open hole. Going to require a patch first be brazed to the seatstay, then a new rack boss silver-brazed to that.
I've done similar to successfully to repair a crack in an old F-frame Moulton. Not "hard", but does require some time and skill which will add to the cost of the frame. Leaving it open is an invitation to water entry if it has not already happened (hoping the bike has been in dry storage).
As a gentle reminder to all: Keep those rack bolts tight! Loose mounting and continued fretting loads from a rattling rack over time can add to stress on rack mounts. LocTite is your friend. Not a factor in all pull-offs, but one that is easily avoided.
Best, Dan.