I've been to 3 interviews in the past month and the feedback is you're too nervous, not what type of personality you're looking for, we want an outgoing, confident person. It's my social anxiety. People don't want to know me. I can do the jobs but they can't see that.
I only apply for jobs I am capable of doing. I rarely get them. Why? Well just crunch the numbers. Some jobs will have 100s of applicants. Even month-long student placements will have dozens of applicants. So let's even it out and say each job has on average 100 applicants. You shortlist this down to 5. That means you shortlist 1 in 20 candidates. You will only shortlist those who on paper can do the job, otherwise it's not worth your time or theirs bringing them into interview. You appoint one.
So for every job out there, you'll have far more people who can do the job than you have positions available which unfortunately means people who are more than capable don't get the job.
I have depression. When I was first diagnosed 10+ years ago I was signed off for several weeks. Now it's treated and managed and I average less than 1 sick day a year, and that's not depression related. But I don't pick jobs likely to make me depressed and I don't tell employers I have it. I get that it's annoying OP and I don't doubt there is discrimination out there. However, you are doing well to get that many interviews and you can fix your interview technique. So either work on that, or think about whether you're applying for the right jobs. Sorry to be blunt. We all have strengths and weaknesses and I have to bear in mind my MH, just as I bear in mind that I won't apply to be a lifeguard, because I can't swim.
Yes, there will be additional prejudice on top of this. But you can help by being selective. And don't beat yourself up. We have all been turned down for jobs we can do.