How to get over performance anxiety in technical interviews?

I've always struggled with anxiety in technical interviews. I think it's due to my working memory seeming to go to zero, so I struggle to solve embarrassingly basic problems. These are problems that I could easily solve if I was alone.

Behavioral interviews and interviews that don't heavily rely on working memory but on past experiences, such as system designs, are completely fine with me.

What have others done to help this? I have done exposure therapy, such as mock interviews, and it helps somewhat, but I seem to regress if it's not constant.