Weird. Birdsite links have just plain stopped working on Safari on my computer. Seems to work in other browsers and Tweetbot but I can't even load the front page on my usual browser, never mind see a specific tweet someone's linking to.
I guess I need to decide if this is, like, anything I actually want to worry about. Oh no! I can't see tweets if I'm on the desktop!
edit: It still works if I open a private Safari window, so I guess Twitter is fingerprinting my browser and decided I'm terrible.