Information is neither matter nor energy so it doesn't break relativity if you find a way to get it somewhere faster than light. Problem is we transmit information via matter or energy.

Quantum entanglement works by having two entangled bits essentially, (how you entangle stuff is far beyond my ability to comprehend) You essentially get a state where you've got two objects in opposite states. Say one is up and one is down. But you don't know which is which. You only know they are in opposite states.

So if you take the two objects to opposite ends of the universe they remain entangled and you can "see" what the other one is by measuring yours and figure out what yours is not. But this is like sending information faster than light by say, cutting a standard deck of playing cards in two, and figuring out what is in the other deck by a matter of deduction. Or taking two lotto scratchers one winning and one losing and randomly giving them to two people, once someone scratches that they instantly know what the other one is. But no matter or energy has traveled faster than light.

Now if you can find some way to manipulate a quantum bit back and forth in a way that manipulates the other bit. Yeah you'd be in possession of some weird FTL communication device. That would open up some freaky causality issues though. The least of which is the question of when. When do the bits flip? Do they flip in your reference frame of now? The reference frame of a distant observer? Perhaps the initial reference frame they shared when originally entangled?

It's pretty much impossible to say as I don't think we've managed to make anything like that yet. We can just entangle stuff and see what it is and then guess what the other one is.