“English GK loses his job to a Spanish foreigner” is basically what’s happening here.
Our fans got too attached to Ramsdale too quickly and started saying “he’s our next David Seaman” etc. it’s clear to anyone that Raya is better than Ramsdale in every department. It doesn’t matter that Raya isn’t the best GK in the world, the simple matter is that he’s much better than Ramsdale and that is what Arteta and the coaching staff see.
Every GK makes mistakes, even Ederson made some against Chelsea.
But the best GK’s don’t let these get into their head and know it’s just part of the game. For Ramsdale if he makes a mistake early you know it will play in his mind and he’ll have a very shaky game because of it, such as punting the ball long into no-mans land out of fear of making another mistake.