As of today (Dec. 16, 2022), many Mastodon and Pixelfed instances are considered "unsafe" to link or navigate to on Twitter.
From @georgetakei@universeodon.com:
This is a simple redirect service for the fediverse, meant to circumvent these anti-competitive mechanisms Twitter has in place. It's made by @matt@writing.exchange and maintained by Musing Studio.
Send me a message with your Mastodon instance URL, and I'll set up a subdomain on unsafe.social that will redirect to it.
Your instance.unsafe.social URL simply replaces your normal instance URL, so you can link to anything there (profiles, toots) like normal — e.g.
https://writingex.unsafe.social/@matt
https://writingex.unsafe.social/@matt/109525313043507213
As always, there is and will never be any tracking involved.