As previously stated, the updates do not always supply release notes. Please see the attached screenshots of the Paypal 5.3.3.7 update and it is clear there are no links to a changelog or release notes of any kind.
The
http://devs.x-cart.com/en/changelog/ site also did not have any posts to this update when it was released since the May 2nd post was prior to the release and the May 12th post was after the release.
The release notes should be made available for all updates, and prior to us beginning the update process.