I can totally sympathize, because I acquired this same characteristic later in life, can you fscking believe? I used to be fearless! (Well, not fearless really, but you know.)

I do have some suggestions for you.

I don't generally recommend pharma, and I don't do this personally, but beta blockers are great for exactly your problem, because they suppress the physical part of the anxiety without doping your brain. For example, many concert pianists use beta blockers to reduce stage fright.

You can't party on beta blockers, and they have few negative side effects, so doctors will give out prescriptions pretty freely, for exactly this purpose, or community mental health centers with limited prescribing rights too.

If you go this route, I recommend getting a prescription of 20 pills, and "practicing" - that is to say, taking a beta blocker and doing some hard, timed test. The first couple of times you take it, you will feel a bit sleepy but you get past that quickly, I am told.

My friend was suffering from exactly this interview terror issue, so he took some meds, and got me to play interviewer with him a few times. At his request, I deliberately made it a bit nastier each time, started doing slightly malicious things like interrupting him or throwing in new conditions. He lost his temper at me once for interrupting him several times, and then we both laughed!

(If you can learn to laugh at this all, you will be happier. I mean, there you are, a big skinbag of mostly water with a bunch of moving parts, made up of the ashes of a supernova, walking into these little rooms to solve bizarre logic problems in order to get food and shelter! Your cave man ancestor would just bust a gut at you. "I had to hunt antelopes and get stalked by leopards, you effete punk!" :-D )

He also started doing leetcode problems with talk radio and the TV on loudly as well. If it was too, too much he'd turn it down a bit, but then turn it up a bit later.

His idea was to get used to it. From hearing his reports of his interviews, I think it has worked for him.

You might not have someone to be a bit sadistic to you, but you can turn on a lot of noise and ask a friend to come in a various times and interrupt you unexpectedly or close the lid on your machine.

The idea is to treat the frustration as a source of amusement, and learn to smile and keep working.

Here are some mental tricks of mine that work.

Breathing control is always good. It just baffles me that this isn't taught to all kids. I'd taught it to people in pain several times, and then one day I fell into a hole in Bali, dislocating my shoulder and putting a big hole in my leg, and I managed to stay completely calm and communicate in Indonesian. (I ended up perfectly fine. I had to wait for the orthopedic surgeon, and I sang long, quiet tones and the doctors were very approving. In New York City, doctors chuckle a bit if you do that, though they never complain, because it's a lot better than screaming.)

I have had many dozens of interviews, and given many hundreds of them. There's a huge level of randomness in interviewing, and not all of this randomness by any means is in the interviewee! Two different interviewers can get an entirely different picture of the same perfectly competent engineer.

If you think of each interview as a lottery ticket, one that you are likely to lose anyway, then it's no big deal if you do in fact lose it. This deprioritizes the importance of the interview, as it should, because few interviews are really life-changing unless you're at or near the peak - getting that CTO job or something.

Another thing that helps me deprioritizing the interview is to think of really bad things that can go wrong and say, "I'd much rather fail the interview than [actually horrible thing]". This is a bit morbid so who knows if it works for anyone else.

None of this job shit is really important. People, health, art and music and science and learning in general, the natural world and the biosphere, these are the important things. Some job is just a job. Yes, eventually without a job there will be negative consequences, but remember, it's a lottery, and tickets are everywhere and the odds aren't terrible. You crank through the motion.

I play a Japanese board game called Go. I got to a medium level years ago and I don't advance because I tend to play the most exciting move over the best move, and I do that because I don't care that much when I lose.

Push the job into this abstract, formal category of a game where you systematically play to win, but don't get so bent out of shape if you lose, and you might be ahead of the game.

The ultimate step in this, "depersonalization" is a trick that works for me and others but it's also associated with various mental illnesses, illnesses which I certainly do not have (because I have the opposite issues, not because I'm fully baked! :-D) but many people do, so there's a little risk.

The idea is to reframe the irrational and negative emotions away from happening to you personally, but to your body, which is often mostly correct. Timothy Leary used to refer to "the robot" in a similar way - "The robot is hungry." "The robot is experiencing a great deal of stress these days."

I had panic attacks for a while, due to my first and still worst hostile workplace (and boy, was it hostile), but I would reframe these as, "My body is experiencing a panic attack," and indeed most of the symptoms are physiological, and this allowed me to stand back a bit and watch the effects with some clinical dispassion. I never got to the point I could laugh at the panic, but I could at least gain a measure of detachment. I was still not functioning well but at least I didn't thrash around.

But I have a pretty good ego, and I used to have a massive ego, so there was no real risk of long-term depersonalization, which is a bit nasty. YMMV, be a little careful with this, you know yourself better than anyone!

Good luck, and I hope one or more of these are useful!