The broadcast rights in the UK are split across Sky, Amazon & TNT (previously known as BT Sport). TNT show one game a week - 12:30 on Saturdays.
My guess would be that TNT have decided they’re going to get more subscribers if they focus on one particular team rather than spread their broadcasts around. You’re probably going to get a lot more subscribers from one team if they’ve got a game on that station every month then you would across the board if everyone was on that channel twice over the course of the season.
Obviously the two most suitable candidates for this were always going to be Liverpool & United. They’re the two clubs with the most fans dotted around the country. The further away the fans are, the more likely they’re going to watch their team on TV regularly. This probably applies more to United than Liverpool, but as far as I’m aware, Sky get to pick the first game of the weekend, TNT get the second and then Sky pick from the rest, so it could be a case that Sky are using their first pick to choose United games for the same reason.
The problem with Alexander-Arnold isn’t so much in games like today’s where he can get himself fired up and he knows that if he doesn’t do his job his side will be punished, it’s in the games against mid/lower-table opposition where he shifts too much of his focus onto the attack and neglects the defensive part of his job.
I’ve said for a long time, it’s not that he can’t defend it’s that he often doesn’t fancy doing it. It’s the dawdling back over the halfway line while an attack is breaking down his flank, it’s the standing still while triangles are played around him, it’s the shirking out of tackles & headers. He knows if he does that against City he’ll be putting his team in trouble, especially with Doku playing as well as he has been.