You're getting a lot of heat from HN about the IQ comment here, instead of being give actual helpful advice or given a charitable reading of the intent behind your statement. (Is it just me, or has HN's quality dropped somewhat significantly over the last ~1.5 years?)
My experience is similar to yours, however. I have managed, led, and been a part of teams at small startups for the last 10 years of my career. I recently joined a name brand, large tech company (not FAANG, but maybe a half step down from there. They certainly think of themselves as a FAANG-type company).
I've had the same experience as you.
There's much more money. Our compensations are higher. The technology choices are more cutting edge and expensive.
But the toolset my team was using to actually develop, is worse than what I've used for the last decade.
The people I interviewed with ranged from extremely intelligent and skilled, to the sort of rude know-it-all engineering type you hear about related to faang interviews. The interview process was so difficult that I was on track to fail it, until an upper manager reached out and personally interviewed me to see what was going wrong, and corrected the process.
But my team, while great people I enjoy working with, are a very, very considerable step down in terms of skill, ability, and knowledge from the last team I managed. And those guys were making easily 50k+ / year less than my current team members.
I also thought I was joining to solve A+ hard problems, and I'm also having a bit of a hard time with it.
I started at the beginning of 2021, I'm taking a couple of approaches, mentally to this. Firstly, I'm not leaving until my stock options finish vesting. So that means I'm in this for the long haul.
Second, the fact that I'm so much more knowledgable than the rest of my team, I hope, should set me up for promotions down the line. I think part of what's going on here, is that this company is so_much_larger than the startups I've worked for in the past, means that ICs genuinely don't get to see most of the truly difficult problems, because true difficulty gets spread out over so many more people, and solved by people higher up the totem pole than a lowly IC. FWIW, this desire has made me really dislike the current Covid WFH arrangement. As great as WFH is, getting promoted is so much harder when you lack consistent facetime with the people around you.
Thirdly, I really, really, really blame the modern FAANG inspired Leetcode interview process. My teammates clearly have the ability to solve leetcode style questions. And in the blue moon opportunity that such a question comes up in code, it is usually solved pretty quickly. But actually important coding skills? I will be keeping this in mind as much as possible when I vet out companies when doing future interviews, and I very much hope this industry fad changes over time.
Fourth: the fact that I can develop so much quicker and cleaner than my coworkers, means that I can take advantage of the fact that this company has many more different types of technology than I would be exposed to at a start up. I will be spending that extra time bumping up my own skillset, so as to be a more desirable candidate once my options vest.
However, all of the above is specific to one assumption: I ultimately like this company, and enjoy the job. I am not working nights and weekends at a company I hate. So if that's the position you find yourself in, I would suggest leaving. The mere fact that something is a FAANG doesn't automatically mean its a good job. Weigh your income vs your options vs your happiness, and make a decision. The "FAANG" title holds very little weight in that decision, except as a good-looking line-item on your resume.