I recently went through a round of interviews at big tech companies, and I found that the coding questions were less stressful than I was initially worried about. Leetcode problems are fair, and it just isn't true that you need to know the trick to pass. It allowed me to get in the door at a company I would have had no chance with otherwise (no CS degree, no top school, small no-name companies, etc)

System design on the other hand... that can be hard to prep for!

The reason companies provide so much info upfront, and even send candidates to leetcode.com, is so that everyone knows what to expect. Not everyone is on HN or is even aware of these types of interviewing trends.