> What if the workplace is not the problem, but me instead?

That's a valid concern. Unfortunately it's one of those things that only _you_ can find the answer to. Getting experience in different companies helps here because you have something to compare your experiences with. Ask yourself what problems you're facing. Write it down; it really helps.

If you are the problem you are also the answer.

I was in similar situation. I didn't quit, and spent quite a lot of time figuring out what was the real issue that me miserable. It turned out it was something I could change without quitting. I managed to change it, but I first needed to understand the real root cause. It is like debugging your life. Mindfulness and introspection are great tools in those times.