I tend to avoid places that whiteboard, the one time I did have to do it I sucked it up only because a friend stuck their neck out to get me the interview. I was told syntax didn't have to be perfect. Yeah I think they may come up with stupid excuses basically to not hire you.

Honestly, interviews go two ways: you figure out if you really want to work there, and they do as well. If they don't want you, assume it's for the best, you would of had to deal with worse: coworkers who hate your personality or have a toxic personality.