Why has YC 6x their legal staff in headcount in past few years?

I believe that one reason is that YC started funding more international startups and it can be legally complicated to onboard internationally-founded companies into YC's standard deal. YC's legal team spends a lot of time helping founders with that and similar issues.

Is this a surprise to anyone?

There are 1.35 million lawyers in America (4 lawyers per 1000 people in the sad State of California) and they are all looking for someone to sue.

If you have a visible business footprint you are a target and have to lawyer up.

Just a Fact of life - Not really a reflection on YC or any other company.

money dried up. they will pivot from being gold-mine wisperers to more mudane shovel-sellers.

I expect they will announce either some startup backoffice/HR/admin tool, or some centralized vetting/investment for the masses, like robinhood but for pre IPO. The former is more likely. maybe start as something crap but hyped out of propo,rtion like a founders master classes by subscription.