BC (Before COVID), I was having trouble finding a qualified person for a role on my team (Operations, not Engineering). I was getting a lot of candidates apply that looked the same on paper but weren't good fits (they claimed to be technical but weren't that technical, poor communication skills, etc.).

So I went in the tool and looked through the discard pile and found more diverse candidates that hadn't been presented to me. One looked amazing—over a decade of directly relevant experience, Oxford grad, etc. I asked the recruiter why she hadn't given me that resume and she said "She's overqualified, she's got 15-20 years experience."

I was livid and said "I don't care if they have 20 years experience, I want someone who is qualified!" We ended up hiring her and she's been absolutely wonderful, and is still on the team ~5 years later.

I don't think the recruiter was consciously discriminating against the candidate, but there were definite implicit biases that she wasn't aware of.

Implicit bias training is now required. I personally found it to be very helpful, and try and be aware of my own biases. I always hire the candidate that I think will be best for the job, but try and always find a diverse group of candidates to talk to. It's a better process, and makes for a better (and more diverse) team.