I am someone with kubernetes in my job title. If you as a developer are expected to know about kubernetes beyond containerizing your application then your company has set itself up for failure. As you aptly said kubernetes is an ecosystem, and the dev portion is a small niche of that.
Makes sense I didn't get the job, I only vaguely know the difference and it was mostly theoretical stuff like CI/CD, but those recruiters really wanted to throw me at random interviews to see if I'd stick :D
PS: sorry I offtopic'ed to recruiter-hating, gonna go find a community for that.
You good homie. I shit on recruiters frequently. I have them hitting me up all the time for in person stuff from LinkedIn when it actively says no in person stuff