Every browser gives me a different result, I guess I can't blame the site for that. But it should perhaps mention which browser would be the most accurate.
Memory bandwidth is completely different on any browser from measured results on my M2 Pro machine. Weirdly, the estimated performance levels and even exact product name differ between Chrome and Firefox. Firefox calls it an M2 Pro and overshoots measured memory bandwidth by 40GB/S, Chrome calls it an "Apple M2 Pro" and overshoots by 80.