The "back to search results" link took ?ref= as it came and was cached
with the page, which ignores ref: the first visitor of a product page
set the link for every later one, and a javascript: URL in ref put
script into the page for all of them (verified locally).
The page now always renders the link hidden and without a target; the
backlink Stimulus controller fills in the visitor's own ?ref= and shows
it, only for URLs of the same origin. The label stays "zurück zum
Suchergebnis": refs only come from the search, and the old check
(strpos() !== -1) always picked that label anyway.
Co-Authored-By: Claude Opus 5.5 <[email protected]>