Finding Former Employees of Client Companies Efficiently

Hi team 👋 I'm trying to find the most efficient way to identify leads who previously worked at our client companies but have moved elsewhere. I have a table of our current clients (company names and domains), but when I go to build a table to find people, it seems I can only pull current employees of those companies. I know I can filter for past work experience after pulling leads, but starting with our entire TAM and filtering down doesn't seem practical. Is there a better way to structure this search to specifically target former employees of these companies who match our ICP? Appreciate any guidance!