I don't think Intel has even decided whether to fuse them off or not. In my newest Intel desktop, a Core i7-13700K, AVX-512 is actually available. It wasn't available on the i7-12700K that was in the same system on the same motherboard a few weeks ago.
i thought the reason they wanted to fuse them off was for all cores being completely compatible (just slower), without the need for the OS to force scheduling on specific cores (I'd guess what would have to happen is if an instruction not available on efficiency core was called, it trap, the OS would see it and then mark the process to only be executable on performance core?)
The official specs for Raptor Lake don't include AVX512 support, so most likley this is just something that slipped through on your system. It might be "corrected" in later steppings or updated firmware. Some early 12th gen systems had unfused CPUs with AVX512 available on the performance cores and firmware that didn't disable it. https://www.intel.com/content/www/us/en/products/sku/230500/...
