Pages page is missing its database after upgrade

I found a pretty obscure bug. Not sure if it is worth investigating, but I describe it anyway.

After the 5.x upgrade one Pages page with a database was showing blank. The linked database just wasn’t there when opening the page on the front end or the Page Editor.
There was no way to rectify this, as there is no database widget anymore and the database and the page were already linked in the ACP.
Eventually checking the MySQL table, I found that the linked page was actually set with the wrong ID, which explained the behaviour.

And I am pretty confident that I know why it happened with just this specific database. In the past, I had created a new version of that database and then moved the old one to a new page URL and the new one to the old page URL that users and search engines were already using. (All using standard ACP functions of course) It seems that your new way of linking the page and the database picked up older page url entries without making sure the latest entry is being used. Maybe it’s worth checking those queries again, so this cannot happen.

(I don’t need help with it for my community. I managed to fix it all on the database level.)