He stated it in an interview given four years ago to GQ magazine: He's a Barça fan.
Interestingly, he will play for Real Madrid starting next season. If he won't wear the blaugrana, it's because Barça believe that with Koundé and Balde, they have the full-back positions sufficiently covered.
What Deco is looking for in that position is depth, substitutes who are up to the task.
Barça Could Have Signed Him Last Summer
Trent Alexander-Arnold was offered to Barça last summer. He had decided not to continue at Liverpool, where he will be free on June 30. But Laporta, with Javier Tebas against him trying to prevent the registration of his signings, chose to give up on him.
The truth is that Deco and Flick didn't insist much either, understanding that Barça is well-served with full-backs.
Alexander-Arnold, one of the great legends of current English soccer, put himself on the market. Meanwhile, the best offer he received was from Real Madrid. He dismissed the others and said yes to the white club.
In the coming days, Florentino Pérez will make his signing for Real Madrid official. Probably from the very day of his presentation, he will have to reset his brain and erase his previous convictions.
For example, the club he sympathizes with, which is none other than FC Barcelona. He explained it this way in GQ magazine in 2021:
Barça's Values
"As a kid, I was a Celtic fan, but now because of the connection with Gerrard, I'm neutral there. I'd say my other favorite team is Barça. I feel they have the same values and beliefs as Liverpool," he said.
He added: "I grew up watching Messi, Xavi, and Iniesta," that would explain everything. Also, that he prefers the Argentine when asked to choose between Messi and Cristiano Ronaldo. "For me, Messi," he declared.
It can be said louder, but not clearer.
Trent Alexander-Arnold: 'I love Liverpool more than anything' | British GQ
At that time, 2021, Trent Alexander-Arnold could hardly imagine that he would betray Liverpool, to which he swore eternal love:
"I've always loved Liverpool, I've cheered for them and played for them. I have no other reason to think about leaving.
Now I don't sit in my room and dream of playing elsewhere. I'm a Liverpool player and love this club more than anything.
I love everything about it. I love the fans, the people, the city. So why would I think about that?".