Poor code quality is almost always a choice by the entire team (and I mean that almost all teams choose poor code quality). Honestly, you can leave, but the next team will likely have the same issues. You can speak up, but doing that too many times gives you a resume that looks like you're a job hopper. So probably your best bet is to coast and find your happiness outside of work. Honestly if you'd had the restrospective and you'd given your feedback, it's unlikely anything would have changed.