Deniers are experiencing a pragmatic split in how best to make use of the Holocaust for their own ends.
For some in the Middle East, it’s more useful to have “A New Holocaust” rhetoric as a bludgeon with which to accuse Israel, so they can’t logically continue to deny it. (Of course that doesn’t stop some from the logical disconnect)
The European branch is now more concerned with expelling Muslims from their countries, so they’re toning Holocaust denial down in favor of an ‘everyone back to your own land’ approach, which requires them to recognize Israel.