Case matters here
The slug on this page is lowercase for readability, but the parameter Outbrain actually sets on a link is obOrigUrl: capital O on Orig, capital U on Url. Query parameter names are read literally by most servers, so a lowercase rewrite like oborigurl is a different string as far as the redirect logic is concerned. If you are rebuilding or testing a link by hand, rather than just reading one someone sent you, keep the camel case exactly as it appears.
What the value actually holds
Most tracking parameters on links like this are opaque tokens, a string of letters and numbers that only means something inside the ad network's own database. obOrigUrl is different. Its value is a full URL, percent-encoded, pointing at the page you were actually trying to reach. That is unusual. It also explains why the parameter looks longer and stranger than a typical click id: you are looking at a URL nested inside a URL.
Set during the widget click
Outbrain sets obOrigUrl at the moment you click a thumbnail inside one of its recommendation widgets, the "around the web" or "you may also like" boxes under a news article. Clicking sends your browser first to an Outbrain tracking domain. That domain needs to know where to send you next, and obOrigUrl is how the destination travels through that hop.
Why this one is riskier to strip
For the visitor, mangling obOrigUrl before the redirect completes can genuinely break the link, unlike most tracking parameters on this site. Outbrain's click server may not know where to forward you, and you could land on an error page or Outbrain's own site instead of the article. Do not edit this one before the click resolves.
For the publisher and advertiser, losing the parameter after the fact just means the click can no longer be tied back to the specific widget placement in Outbrain's own reporting. Compare this to Taboola's tblci, an opaque click id with none of this URL-carrying behavior, or to Yandex's yclid from its own ad network. More parameters are indexed at the link decoder hub.