In Add link interface of Wikidata on the page https://ru.wikipedia.org/wiki/Feelings?uselang=en —
(I entered https://en.wikipedia.org/wiki/Feelings_(disambiguation) in both fields and tried to submit the form)
jQuery.Deferred exception: this.element.tipsy is not a function _create@https://ru.wikipedia.org/wiki/Feelings line 10 > injectedScript:21:385 $.widget/</prototype[prop]@https://ru.wikipedia.org/w/load.php?lang=ru&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Cjquery.ui&skin=vector&version=13d05:415:310 _createWidget@https://ru.wikipedia.org/w/load.php?lang=ru&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Cjquery.ui&skin=vector&version=13d05:418:389 $.widget/$[namespace][name]@https://ru.wikipedia.org/w/load.php?lang=ru&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Cjquery.ui&skin=vector&version=13d05:414:667 $.widget.bridge/$.fn[name]/<@https://ru.wikipedia.org/w/load.php?lang=ru&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Cjquery.ui&skin=vector&version=13d05:417:491 each@https://ru.wikipedia.org/w/load.php?lang=ru&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Cjquery.ui&skin=vector&version=13d05:5:285 each@https://ru.wikipedia.org/w/load.php?lang=ru&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Cjquery.ui&skin=vector&version=1…
Caused by T117720: Remove use of jquery.tipsy from Wikimedia-maintained code in some way that I cannot debug at the current moment.