The problem is outside the big companies everyone knows, it’s hard to get documentation on a companies interview process.

Glassdoor exists, but often is little help, as there’s a complete lack of information about the actual process, it seems too included only people who didn’t get an offer complaining about something that may or may not apply to you, etc.

Even the sites made specifically for aggregating those sorts of companies often fail. I’ve looked at them and seen stuff like “X company, but only very specific team” or “Y company”, but when people talk about them nowadays, they seem to have switched to utilizing leetcode or similar for screening or something. And god forbid you out any filters on.

Very much this. I've never actually done a single leetcode problem and never will. Recruiters will tell you what the interview process is like (if not, just ask). If it is based on whiteboard puzzles like this, just refuse. Be sure to tell them why you're not interested!

We can improve the maturity of hiring in this industry but only if we collectively refuse to participate in these bad practices.

As long as newbie frontend engineers out of coding bootcamp continue dominating the hiring market this will never change. It's factory mentality.