Reddit, YouTube, facebook and all of the other social media websites track the urls I copied. Whenever you copy a link, check out, it is not the actual url and/or it contains a track id in the url. I can’t share anything with the people any more, and click their links, because I hate being tracked.
Social media sites live as advertising vehicles. Being able to show numbers related to users showing links helps them sell advertisements.
It’s reportedly why Bluesky redirects links in the app to a referrer – so websites can see how much traffic they get from there and have a reason to post on the network.
Whether or not this is a good thing, and how much tracking is acceptable, is an entirely separate discussion. (Which should really include words like “I regularly donate to my Lemmy instance” or their equivalent…)