I’m now in a very similar situation after the company I joined got acquired by a larger company—both have been the largest companies I’ve ever been part of. I also have not enjoyed the move to Microsoft, and I honestly go back and forth on whether I stay or leave.
I’d advise you to find something else that’s a great fit, which may take longer than you’d like. But try to learn and get as much out of this experience as you can while you’re there. There are probably some processes, systems, or collaboration with other teams that can benefit you in future roles/interviewing.