Been seeing this message consistently on intrapage click-through windows (or whatever the terminology is). In my web browser which is Brave. Haven't checked the Steam client because haven't bothered using it lately. I had it open a few days ago and didn't notice it on the client. But it's been happening on the browser for several days now. Perhaps it's an adblocker side-effect but I'm not gonna jump through hoops if Steam cannot get its busted-ass website sorted out.

Doubt it's a client-side browser issue, though, because Google is seeing it too. I ran a search using the titular text in the query, for the past week, and numerous Steam pages are showing up in the results having that text.