M4's GPU does not support 64 float. So, yeah. No hardware support, so what are you expecting? The fact that it comes close is pretty impressive.

These tests were done on the CPU cores, not on the GPU. In every test I ran the A18 chip blew past Intel's Core 5 on GPU performance.

There were a series of other benchmarks too, but the Hackaday article only highlights HPL as that was the benchmark that changed my perspective on Intel a bit. This was the first X86 chip to trade blows in efficiency (and idle power draw) with Apple's M3/M4 (I don't have any M5 to test with right now).