Then the issue isn't with the tests necessarily, it's with employers using a test of Skillset A to screen candidates for a job that is 80% Skillset B and 20% Skillset C. That doesn't make the tests ageist (which I suspect was included mostly as click bait), it just makes the hiring managers at these companies bad at their jobs.

Raise your hand if hiring managers being bad at screening technical candidates for highly technical roles is surprising to you.