They will share leetcode question link and keep changing the question until they find an unsolved question. No issue in this, but when they change question, they can offer different level question as well(for example earlier I was given easy question but since I had solved it, interviewer kept changing question and ultimately gave an hard question, which makes the interview process unfair for people who practice). So for candidates I would recommend you to not use your main leetcode account and use a mock leetcode account.