I was thinking the same thing. Over the years, I’ve seen a few of these and have always wondered which of my posts was affected. It seemed logical to want to see which post I lost or gained (so far only lost) rep on. However to be honest, it just occurred to me that this would be pointless.
When this happens, we don’t lose/gain rep from anything that has to do with the our posts; the change is due to the user, so it doesn’t really matter or have anything to do with us. Obviously, since our rep does get affected, we would need to know why it suddenly changed, but knowing the specific post that was affected is useless because there’s nothing to do with that knowledge.
If you lost some rep from a deleted user who had up-voted your post, you don’t need to improve it because that’s not why you lost the rep. If you gained some rep from a deleted user who had down-voted your post, you don’t need to, well anything; just be happy about the rep-bump.
There’s really no point to knowing which post(s) were affected.