Leave.
Burnout is a serious illness and debilitating. It can take months-to-years to recover and you'll always carry around the scars. If all you feel is stress and you have no control over how much stress you feel, that's the recipe for burnout.
Being professional about it is handing in whatever required notification the company requires and gracefully offloading your work to the team.
From a hiring perspective I think anything less than a year is a honeymoon period. If you interview the company well it can still take 3-6 months before the organization shows its true colors.
That being said, finding the right company for you is the hard part. Some folks do actually thrive in scenarios like this and enjoy migrating a code-base to a healthy state and correcting organizational communication issues.
Not my thing anymore. The demands on developers these days is to turn us into company therapists. We're supposed to bridge communication silos, get groups talking, mentor and grow staff, train management in how to manage us, etc. And we're supposed to continue with solving technical problems, generate new ideas, and be a source of innovation. It's a bit much if you ask me.
One strategy that I think is important to finding the right place for you is to know what your values are. If you are someone who values maintainability you're going to have a hard time fitting in with a team that values velocity: they're going to move fast and change APIs all over the place and check in the first thing that works and iterate from there. It will drive you up the wall. If you know what you value most you can interview the company to find out what they value and see if the intersection is large enough to convince you that you won't be alone in what you care about.
To find out what your values are you have to think hard about what you think is important to you and write them down. Try to stick to single words like: maintainability, performance, readability, etc. Also look back on your work objectively and see if any of those characteristics come out (we like to think we value certain things but what we actually do in our work sometimes contradicts these notions). Note down any new ones and add them to your list. That list is your list of values.
It's also worth writing down your, "engineering principles." A one or two page summary of how you approach software development. I like to take the list of aphorisms and maxims that I often find myself repeating and sticking to and use those as headings. Then I explain those headings and what they mean to me. You may find some new values in here to add to your list.
Hope this helps and good luck. Sticking with it for six months and realizing this isn't the right fit for you is good! Be professional, give your notice, and start looking for a team that will better fit within your values.