Ageism is very real. I worked with a guy at a startup who literally said about a candidate, "He's too old to work here." Meaning he wouldn't be able to fit in and relate to his coworkers regardless of his technical ability.
Sidenote, he also voted to reject a candidate because, "we have too many white guys." (He himself was a white man)
Now the guy who said that was one of the few people in my career that I truly disliked working with but I'm sure for every guy like him who says those things out loud there are 10 thinking it to themselves.
One solution I've found is to increase the frequency of interview shadowing. That way you at least have two people in the room, hearing and seeing the same things, and able to catch and call out biases.
Sidenote, he also voted to reject a candidate because, "we have too many white guys." (He himself was a white man)
Now the guy who said that was one of the few people in my career that I truly disliked working with but I'm sure for every guy like him who says those things out loud there are 10 thinking it to themselves.
One solution I've found is to increase the frequency of interview shadowing. That way you at least have two people in the room, hearing and seeing the same things, and able to catch and call out biases.