Or...
He's just coming back from injury and hit the ground running. He's not played a lot of football in the last two years and is doing his first run of festive fixtures. He's then picked up a knock v Spurs and not been himself since. Needs a rest.
No pre season, comes straight into starting 11 , playing in the most fast paced physically demanding league in the world ,called up for his country , then comes into a schedule that has 4 games in 10 days and gets a knock in the first one against Spurs, not rested. I’m thinking it’s fatigue too tbh