If you go regularly the concentration of PFAS in your donated blood would be lower compared to going more sporadically.
https://medicalxpress.com/news/2024-02-danish-drug-chemicals...
for a drug that appears to lower PFAS levels. I'd be concerned about where the PFAS is partitioned in the body: giving blood isn't going to make a big difference if most of the PFAS is in your fat.