It's about now that we should point out that it's still April Fools in America, so this could well be a bit of tom-foolery.
In addition to the deleted tweet, a video confirming the title's release on the Epic Games Store was also deleted.
Thankfully Wario64 managed to capture them both:
Borderlands 3 was announced last week at PAX East, where Gearbox promised further information on April 3 – making this feel more like someone in the marketing team jumped the gun rather than a fleeting April Fool's joke.
Guess we'll just have to tune in to find out.