[joshspankit]

TikTok has possibly the most nefarious version of this: When someone shares a video, a link is created that’s specific to them. It’s a short link that looks like a regular one, while the tracking params are shown only after someone goes to the link and the shortener resolves it. If it opens in the app through deep linking the tracking has happened transparently.

[explaininjs]

This (ostensibly) empowers the user-facing "feature" whereby you're presented the "User XXX is on TikTok, you should join them!" modal when you click their link. Which is perhaps better than no end-user impact at all.