https://en.wikipedia.org/wiki/Ruinerwold_secluded_family

Instead, everyone expects there to be a magical unicorn out there who has decades of experience as a senior at multiple FAANGs but lives in Warm Spit, Missouri and is willing to work for the average Walmart wage in Warm Spit (locality adjustment, surely you understand why we must do this). Shrink your pool to your local area. Even if you allow remote work, require a physical interview at your office. Stop screwing up the process by worrying about edge cases involving unicorns flying across the globe to meet you. Once you stop chasing unicorns, most of the fraud goes away because it's the unicorn chute that's letting the fraudsters into the process.

But seriously, stop getting rid of good employees and stop refusing to build up employees from within. Very few are going to get hired away if you treat them well. The few who do leave will either be treated poorly at their new employer and want to return or be treated well, which means that employer isn't gaining some advantage over you by treating their employees lesser.

Of course, if you're just trying to get a bonus for cutting labor expenses a few percentage points before you parachute off to somewhere else, then you and the company that tolerates this both deserve to suffer. No doubt you'll both be at your congress critter's door to demand access to the global market because you believe skill is based on how little an employee is willing to accept in compensation. In a labor pool of over 150 million, no doubt it's true that you can't find anyone who knows React or Spring Boot.