What is this?
The idea behind this service is completely stolen from this random conversation on Twitter. The only difference is that we keep serving the second URL to bots (or things that have a user agent that looks like a bot) all the time.
Link previewing is annoying if you want to surprise people. Most of the time, people will also not click on the link and stop after reading the headline. This will trigger people to write click-bait titles even more and that's not a good thing for anyone. But mostly for trolling purposes.
Do you mangle URLs?
Oh yes. We do all kinds of unspeakable things to your URLs. Strip tracking codes, add more, change referral values and what not.
I once had a link shortened where you could hand in two URLs. One where it should redirect and one where the first redirect should go to.— Andreas (@i_x_s) August 24, 2019
Perfect for messing with these link preview fetchers.