It might look that way to someone who's just recruiting, but if it got to the point where OP was burnt out, it's probably more than zero. 4 years isn't really that much, especially if they were using a relatively recent framework or something.
If they were building flask applications then, and refresh their memory, they probably already know how to become productive contributors on a team.
The burn-out happened to a major degree at my last place of employment. I was an early employee at an electronics startup and I was working around 17 hours a day migrating an early version of the web application from PHP into Node, programming arduino and raspberry pi boards, adding various payment modes to an android application, and writing server code in Haskell (a language chosen for no good reason other than it sounded cool and nobody except me could even read the code, the person who wrote it initially having left). 10 months of this ultimately took its toll.
Ya you're fine. Seems like you're someone who's been through some trials, I'd be happy to work with you. That's a series of messy problems and you learn a lot, including humility.
My advice as someone with perhaps a less intense but similarly tumultuous history, is that you should learn to tell that story in a concise and useful way to a variety of types of people and on your resume. Practice with any random recruiter call. Anyone would agree with why you left the industry for a bit. Also try to concisely describe what you genuinely want to be doing now, which I can provide some examples for if you like.
