I'm sorry you're going through this. You're absolutely right that working harder is not the solution.

My advice would be to talk to the team or HR about your negative experiences.

If that doesn't help update your resume/portfolio and start finding a new job. (while you're still employed) Please don't stay too long in such a toxic environment - it's not worth it. I don't know you but I don't think you will have a hard time getting a new job.

You can get rid of the imposter syndrome with the help of a cognitive behavioral therapy.

I wish you all the best.