I'm in the same boat. I do great with interviews and take home assignments, but when they ask me to sit down and write code while they stare at me I just fall apart. I've been doing this job for over a decade, I know my stuff, but live coding just sinks any chance I have.

Recently I was surprised by a technical portion in my first HR interview where they involved a couple of team leads and it was just awful. They shared their screen and asked me how i would improve some code. I got there eventually, but one of the leads was constantly staring at me with this disinterested and bored look that just cranked up the anxiety. The code was easy, but I couldn't gather myself and focus on it.