What did the neighbor do? Sabotage the drainage?

There is a well known case in Langley where the neighbor did not like the new construction, so he put plumber's putty in the drainage, in an effort to cause ongoing water damage.

The neighbor was more bitter than smart

No, you do not need to disclose. It was fixed.

But, your agent should be able to advise you on this issue.

The Q is, is it a known defect?

If there were water there now, that would be a known defect. But it's not there now. So nope.
If there were an existing condition like a leak or faulty drainage that would lead to water when it rains, that would be a known defect. But you said they fixed it long ago. So nope.
Here's the tricky one: If there were mold from the long-ago water, never treated, that would be a defect. The Q is, is it known? If you know there's mold there, you need to disclose. If you don't know, well, are you going to find out or not? If you do a pre-sale inspection, you'll know and have to disclose. If a buyer does an inspection, finds it, and backs out, you'll know and have to disclose to future buyers.

Why doesn't seller have to disclose?

nope. but a good house inspector would find damage/look into records...

no

If there was water in the basement years and years ago, but it has not been even a slight issue in all of those years and it was due to a neighbor's failure to maintain property which has since been remedied, is there a duty for seller to disclose to buyers? In VA.