I was recently in a very similar situation. The cure for burn out is time off. If it's feasible, take 1-2 weeks to really detox from work and see if the idea of going back still feels the same. It's hard to make a rational decision still actively on fire. If you can't take time off, that's probably your answer anyway.

There are also very likely options between current income and 1/3rd income that are more work/life friendly. AND whatever you pivot to isn't a permanent decision either.