PFF has evolved a lot since the Collinsworth acquisition. Do they get everything right? No, but even the pro evaluators don't. What I've learned is that every team in the NFL is using their data to make decisions on and off the field. Not necessarily their grading, but they can tell PFF to show them every turnover-worthy play from Josh Allen in the last two years and get all of the videos almost instantly to see what's causing them (and decide for themselves if the plays were turnover-worthy). Or get every video where a LT got a negative grade so that teams can identify and exploit that player's weaknesses. And they can get incredibly detailed game planning information that I wish I could pull (ex. what route concepts do teams run when a certain WR lines up in the slot).
They get their grades/stats by watching live tape, and gave him two turnover-worthy plays last night. You're right that they don't adjust for situation, but few stats do beyond EPA and DVOA, although those are based on results (a tipped pass getting intercepted is a negative even if the QB had nothing to do with it).