In the approximation of the True Laws Of Physics which is in use today --- The Relativistic Standard Model --- FTL (and subsidiarily time travel) is nonsense. Like, it's gibberish. It is a description of a situation which not only does not happen, but which is a mathematical falsehood. It is impossible. It is like violation of conservation of energy, or violation of entropic developments.

The maths plainly states that assumptions like that leads to a contradiction, and we do in fact know that the Standard Model is complete and consistent (i.e. cannot encode formulas as objects).

Any hypothetical scenarios involving time travel will invariably be contrite, non-causal, and require classical mechanics. It is fiction, make of it what you will.