Ask anyone with experience conducting tech interviews. They'll say that Leetcode Hards are never asked. It's well-known knowledge at this point. Note: Hard could mean different things for different people. I'm referring to the "Hard" category on Leetcode. Yet Leetcode and GeeksForGeeks will never remove Hard level questions. Why? Because they're major money makers. Hard questions give you the illusion that you need to prepare more. Imagine this - if Leetcode questions stopped at Medium, many people will consider their prep done. They will leave. The trick to make them stay - give them harder questions so they feel like they have more work to do. To be fair, the easier ~20% Hards can be asked in interviews, but 80% of Hards will never be asked. Let's call these what they are - Unreasonable Problems. It's unreasonable to think they will be asked in interviews. This is extremely harmful. It makes you feel like you're always behind. Think about this - if there were no Unreasonable Problems, you will feel a lot more confident about yourself. You will focus on improving other skills - such as System Design or mastery of Medium problems. Instead, you're always looking up to Hard problems and feeling inadequate. GeeksForGeeks is another site that thrives on creating as much content as possible. They have an army of students in India who write articles. Do you really think that these students know what's being asked in an interview? They don't, which is why they often make content that's completely out-of-scope for interviews. These websites are taking advantage of your insecurities. Don't let them. Use a more trusted resource with known authors and curated content.
Balance Check 
Sometimes, doing hard problems gives you confidence. If you solve Hard problems, then Medium problems seem easy, right? That's a good feeling to have. Just don't waste too much time on Hards.
There might be a small minority of interviewers who ask Unreasonably Hard problems. I would estimate, maybe 2 out of 50 interviews. However, should you really prepare for such outlier scenarios? I wouldn't. But if you have time and interest - sure, go for it.