I think you're saying "how do we know this isn't the normal amount of Phd people who leave every year/administration
While we don't have PhD numbers the Trump administration fired a large amount of people so no matter some portion of those had Phds therefore it must be higher than the previous administration
"Science’s analysis found that reductions in force, or RIFs, accounted for relatively few departures in 2025. Only at the Centers for Disease Control and Prevention, where 16% of the 519 STEM Ph.D.s who left last year got pink RIF slips, did the percentage exceed 6%, and some agencies reported no STEM Ph.D. RIFs in 2025."
While we don't have PhD numbers the Trump administration fired a large amount of people so no matter some portion of those had Phds therefore it must be higher than the previous administration