The on-loan Derby man was not punished by referee Russell Booth for the incident that led to Johnson going to hospital on Saturday, but City were so incensed by the challenge that chairman Peter Ridsdale asked the FA to review the footage.
As a result, the Jamaica international has been suspended and Palace boss Neil Warnock is unhappy about the decision.
"The referee told us after the game that he saw it and thought it was inconclusive - so I don't know what has changed his mind," he told the South London Press.
"There are just no comparisons between some of the challenges I've seen that haven't been punished. That's Claude done for the season now."
Johnson spoke about the incident for the first time on Wednesday and told Wales Online: "It's clear for everyone to see what went on and it's clear in my eyes. I'm disappointed with the player."