Then you weren't paying attention enough, there were several posters on here immediately after the match posting repeatedly about how Ten Hag should be gone, and arguing with posts that were sympathetic to him, rather than celebrating the win. There was one poster who kept replying "8th" to posts suggesting that winning the FA cup was an achievement that should allow the manager to stay on. It was all very telling, and your doubt is irrelevant in the face of what happened.
You may not have been one of them, and maybe you really do see yourself as supporting the club while those who want the manager to stay are putting him above the club, but trying to paint those who agree with you about wanting the manager out as putting the club first is nonsense given how plenty of them were aggrieved we won because it could strengthen the manager's position.