The problem you're asking them to solve is a legal one, but you are not interviewing lawyers. I have never worked for a single employer that didn't require an NDA, and the NDAs are always written in a way that can be easily interpreted as "do not tell anyone anything about what you do here".
The question is not tell me what you do in your current job. The question is describe a technology or system that you understand well. Do you understand how the underlying systems work? You don’t have to tell me that your current company uses kubernetes to describe how kubernetes works. Your current job can’t keep you from describing how kubernetes works. Kubernetes is just an example here you could pick any technology that you’re comfortable with.
You're asking them to explain a technology they use while expecting them to tiptoe around what they're actually allowed to say about how they applied the technology. And you say this replaced your system design interviews. It sounds to me like someone explaining what Kubernetes is won't do nearly as well as someone who can explain in-depth how they applied Kubernetes to their job.
