Meh. I think the ratio didn't change at all, it is just that contractors jacked up their rates to cover the added NIC. To me it seemed like someone in HMRC/govt got a "win" but all the govt agencies just had to pay more for their contractors. Almost zero-sum but actually net negative because of added bullshit.

I left UK when it only covered govt agencies so not sure what the mitigations were for private sector but I'm sure many found a way around.