Corrupted output

Hi

I have rather strange problem. On one of my sites, if search has no results, search form and breadcrumbs get corrupted to something like “��䙫an��u��”, which sort of points to the wrong encoding.

Here is a link to empty search:

https://www.beltsfromoz.com.au/?s=craptest&post_type=product&type_aws=true

You can see search form at the top is corrupted and breadcrumbs at the bottom too.

If search returns valid result, everything is fine, only for empty search. And only on one site. I have other sites that run without issues.

Any ideas what can be wrong?

Thank you