A good thing about tech is that if you have a spare device (even a cheap single-board computer like a Raspberry Pi or similar cheaper one, or a partly-broken laptop) or a working virtual machine, you can break things. That’s a core characteristic of the old-school hacker mindset, to try stuff and break stuff until you understand stuff. Usually, the worst case, you just reinstall the operating system and have a fresh clean environment (or, better yet, you restore a backup you made! Learning how to fail gracefully is a great skill)
I bricked a certain wacky laptop setup twice and had to start over (luckily with backups) just trying to get a custom startup loading screen. But once I realized why it was breaking and how to avoid it, I had a cooler looking computer!
xcancel is just one Nitter instance (just like lemmy.ml is one Lemmy instance). I recommend sharing the load around to other working instances, or better yet, as Avatar of Vengeance mentioned, use the LibRedirect browser extension which automates this for a huge range of other websites.