I suggest practicing over and over again to reduce your anxiety. We all feel anxious when doing a whiteboard or now VC interview where they can ask you anything and you feel like you have to instantly answer.
VC interviews also seem very high pressure! I've met folks making funding decisions, but never been in the hot seat with them. It does seem closer to the "walk me through your portfolio/a project" interview than a whiteboard interview. Although obviously the stakes can be much higher.
Anxiety isn't related to experience (or actual competence). When it's on the level mentioned, what works is CBT (if you're lucky). That may include practice, but it will certainly not be the only element.
And for experienced people, be ready to say what you left your most recent job, what you gained, what did't work well, is there a noticable arc to your career, if you want a new job type how are you prepared.