Apparently, per https://gerrit.wikimedia.org/r/#/c/199679/ , ConfirmEdit is attempting to find which links were added when viewing the edit form (action=edit). That patch changes it to do a slave query, but I don't think any query should be necessary.
On action=edit, no links will have been added yet as they're just editing the page (unless it's a preload, but that's relatively rare).
And most importantly (regardless of whether it's a preload) you don't know the final links they're adding (if any) until they save.
(Though it's possible to try to show it on preview speculatively for a better UX along the lines of https://git.wikimedia.org/commit/mediawiki%2Fextensions%2FConfirmEdit/7e0651a3c412a1b35096bc666901c43dcffeaa8a).