Someone signed my PGP key, by accident (we have never met, but I know the person a little).
The wrong signature was uploaded to the SKS pool. Is there anything we can do about it to improve the web of trust again?
They can revoke the signature using the revsig command of
gpg --edit-key then re-upload the key to the keyservers. Alternatively you could meet up with them demonstrate your bona fides and make the signature retroactively true.