Wow, do you use Spark in production? I can't claim to have much experience with it, I just played around with it a loooong time ago, but I was impressed. I thought it went out of use along with Hadoop and HBase, glad to hear this is not the case. Are you hiring? :-D
I had a guy tell me he had experience with Apache's mod_rewrite module and, when asked what its purpose was, he said verbatim "It gives you, like, more commands and stuff."
Other questions were met with equally disastrous responses.
Me: you've listed Java as "Expert", perhaps you could discuss about <favorite footgun in project>
Interviewee: sweats for a bit, finally admits only used Java factory factory and copied lots of code
Me: ok great, let's move on, you've listed Rust as "Intermediate", lets...
Interviewee interrupts, admits they know how to spell Rust and watched a couple of videos of crabs