I am in the midst of one. It has been about a year and a half, plus or minus, and it has taken a tremendous toll on my well-being. I find it especially difficult to deal with the mismatch between my sense of what I can do, which is calibrated to my former self, and what I can actually deliver. I desperately need to believe that what I am going through is a temporary perturbation, so I keep trying to "shake it off", a…
What was the event that caused you to burn out in the first place? It looks like you expected at least social (if not material) recognition for some herculean effort that you went through - it failed to arrive when you cliffed out, and you're not obtaining that due to the circumstances in the meantime?
If I'm right (I may not be). My suggestion would be to make sure you're on teams or a project where there is a direct relationship between effort and reward, or where you can work on small projects that don't come with a 'big payoff' but can rebuild your confidence that you can provide value to your org. You should also try to be under a manager that is good at recognizing (verbally if not anything else) your achievements.
If you don't think you can find that easily, take some time off and go drive for lyft. (Don't expect to make too much money off if it, so only plan to do it for a short bit). There's a direct relationship between effort and reward in that industry.