I had the same experience however not with whiteboards but with take-home assignments, I was looking for a job while still working crazy hours at my previous co

I had the same experience however not with whiteboards but with take-home assignments, I was looking for a job while still working crazy hours at my previous company. I often had to code in the late hours of the night or pull all-nighters for days straight to deliver these tests, and most of the time I got rejected with barely any explanation, one time the company just ghosted me and didn't even give me a proper rejection. It wasn't just a defeating experience, it was affecting my sleep and my health.