that is why you have to first verify whether they have a master's in CS, if your requirement asks for that. you call the university and find out. if they don't, you can discard the candidate. then, you can filter on the visa requirement etc, and only after doing all these obvious things you go on to your requirements.

this also means you don't need to do leetcode interviews. anyone from a decent university with an actual degree will be able to code, or quickly learn how to. you said it yourself - too many candidates, so no time to do leetcode BS.