From what I can tell DevOps is the hardest thing to hire for right now, and it commands the highest salaries. It's tough to find someone who can code and troubleshoot code problems, but also has all the skills of a sys/net/cloud/k8s admin, and is willing to put up with the higher stress of that role.
Most qualified people have already done their best to get a job they're happy with. Personally I'm not making FAANG money, but as a self-employed freelancer I still do pretty well. So it's hard to see hidden-salary listings as anything other than a waste of time. 90% of them will come in too low. Things like a four-hour coding assignment just prove to me that it's smarter not to bother. If you make it that pointless for qualified candidates you'll only hear from the unqualified ones.