PFAS are hydrophobic molecules so, not knowing what to do with it, your system will store them with the fat (also hydrophobic). Doesn’t do much in itself (depends on the exact molecule though) but the issue is bioaccumulation and amplification: imagine the food chain as a large hopper, sprinkle a bit of none biodegradable shit on top and imagine the dose you get at the bottom of it. In larger quantities you start disrupting processes in the body often leading to cancers or a myriad of symptoms caused by endocrine disrupting
You might not be better off with metal ustensils, loads of PFAS are used in the manufacturing process and end up in the finished product.
A professor once told me: “You cannot avoid contamination, you just have to diversify the sources.”
FYI items labeled as microwavable are tested to assess what leaches in the food or liquids under normal use. The leachate has to be identified and approved by the FDA (doesn’t mean safe but at least ok-ish)