That is 3d-peek on the footnote itself, not the link in the black box.

Same goes for "hook links" in reference lists (wikilins from a footnote with ex https://en.wikipedia.org/wiki/Template:Harvp which links to a reference listed below). Also previewes the home screen. (Most likely because it's a section link like #foo which in preview mode tried too search for #foo instead of [[article title#foo]]. Somewhat related to T124291?)

https://github.com/wikimedia/wikipedia-ios/pull/415

@Josve05a this should be in the latest beta. Let us know if its resolved to your satisfaction.