In fairness, Southgate only played Trent for about 30 mins in the World Cup in Qatar, so clearly he's not that bothered about having to play him.
Obviously he has given him a go in midfield yesterday, and there are plenty of arguments you can make about whether he should continue with that or try Gallagher, Wharton etc.
But if hes prepared to try things like that out, I don't get why you wouldn't try Bellingham a bit further back and give Phil a go centrally. Bellingham, like him or not, is a brilliant player and if Southgate wasn't so concerned with being overly defensive, he could try and give England a bit more of an attacking mentality and play Palmer/Saka - Foden - Gordon behind Kane