It never was relevant, it's a mater of who's participating in the fad, and the popularity is waning, but not everyone hops on to the latest fad at the same time, so you might need to do some intelligence gathering to find out if any specific company is using them.

Companies still need to verify your competence. You should be prepared to answer LeetCode mediums and ensure that your soft skills are strong. What you did at your previous company and how likeable you are are more important than ever.

Not at all. A couple of years ago the company I worked for told us "no more quizzing" for new hires. Like, none. And that was before an LLM could tell you the answer to every leetcode question in a single AI assisted search. I really think this is part of the reason juniors cannot get hired. They have no track record and quizzing seems to be indefensible now as a matter of employment law. You really have nothing to look at but track record now, and juniors have none.