I looked, and you are correct. The 23.9.X drivers are actually gone even from the previous driver link on the driver page.
This is purely just a theory I have, but I believe it was due to the freezes people, including myself, experienced with all of the September drivers. This is purely speculation. I was unable to find any information on this specific situation.
I think AMD did the right thing here. There were numerous users that experienced freezes when interacting with browsers, Steam, and other applications requiring a driver restart to fix the issue. For me restarting drivers only fixed the issue for a few minutes. Because of this, I moved to 23.9.1 and eventually, further back to the 23.8.2 WHQL drivers until the 23.10.2 drivers were released.
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