What Quora puts on the link
Quora's Conversion API documentation says that when a user clicks your Quora ad, "a qclid parameter is appended to your landing page URL." It is the click ID that lets Quora credit a conversion to the ad click behind it. Quora's own example value is 0|212106239366182|0. In a URL the vertical bars are encoded as %7C, so the same value arrives as 0%7C212106239366182%7C0, and Quora accepts either form when it comes back. Quora does not publish what each of the three parts means.
"You will not see the qclid"
Quora's help center adds a warning that catches people out during setup: "During testing and setup, you will not see the qclid appended to your landing page URL. The qclid operates on the backend." A test click with no qclid on the URL is expected. It does not mean the integration is broken.
How it gets back to Quora
A click usually happens well before the sale or signup, so the value has to be stored. Quora gives two routes. With the Quora Pixel installed, the pixel saves qclid from the landing page URL into a first-party cookie named quora_qclid. The cookie lasts 90 days and is overwritten by each new Quora ad click. Without the pixel, the site reads qclid from the URL itself and keeps it in a cookie, the session or a database. Either way, the stored value goes to Quora as click_id when the conversion happens. Quora says events sent without a valid click ID are accepted but not attributed to any campaign.
If it gets removed
The page looks the same without it. Removing qclid before the pixel or the site stores it means that visit cannot be tied to a Quora ad later. For click IDs from other ad networks, see rdt_cid for Reddit and twclid for X, or browse the link decoder hub.