Not sure. Football fans have been detained in advance before I am not sure under what guise, but on intelligence they would commit trouble I guess.

This is to largely stop people like Just Stop Oil, and rightly so. Everyone has a right to protest, buy not to close whatever roads they like and bring the country to a halt. I don't have a right to close the M4 because Cardiff Council didn't pick my bins up last Thursday or whatever. Just Stop Oil etc pushed the law, and well.. there are consequences. The law changes.