Holy shit, this sounds exactly like something I might have written. Feeling exactly the same way right now. I don't have any real advice because I have the same questions and am also trying to figure it out, just wanted to let you know that you're not alone and I'm somewhat relieved to know I'm not the only who feels this way. So thank you for making this post.
Sounds like the learning curve is just too steep, and you're interviewing for something too hard. Maybe lower expectations and take an easier to qualify for job so you can practice at your leisure. Two months is actually quite short for job searches; expect at least 4 months even if you're moderately good.
Try getting a job on a smaller codebase and in a language whose ecosystem you understand very well (if there isn't any, work on it in the spare time you have now). This will significantly reduce the initial hurdles on the job for you.
Perhaps you should actually "burn out"? Once you burn out there is nothing left to burn. Can't light a fire in that area for awhile. So, let yourself fully "burn out" for that "place".
Take your skill elsewhere. Apply it somewhere else in some other fashion. If you return to the original place then good. Otherwise you're elsewhere and doing different or even the same things.
If you find out, let me know.
Sounds like your approach to work might be the problem. Mix it up. Pick a simple side project and start then finish it. Doesn't even need to be software. The act of finishing it is the important part.
During a funk in my 20s I went into a city Id never been to and spent the whole day looking at art. Thoroughly bored out of my skull. But over the next few days I had so many ideas for things.
Perhaps you need to get really thoroughly and industrial-strength bored?