Search box HTML tag not properly closed

Hi All
Whilst debugging the search icon in the header menu of one of my client sites, I noticed that the HTML “a” tag is not properly closed. The first couple of lines look like so:

<a href=”?s=” data-avia-search-tooltip=”
<form action=”https://mysite/&#8221; id=”searchform” method=”get” class=””>

with the form being inserted before the “a” tag has been closed. Further down, the rest of what should be on the first line appears after the form element has been closed. It doesn’t seem to affect the searchbox and it visually comes up fine (tested on Chrome). Still, it might break in the future so a fix would be much appreciated.

Link to one of my sites is provided.

Many thanks
Diana