FYI, Burnout is not well-defined: "with symptoms characterized by 'feelings of energy depletion or exhaustion; increased mental distance from one’s job, or feelings of negativism or cynicism related to one's job; and reduced professional efficacy'" (https://en.wikipedia.org/wiki/Occupational_burnout)
... So, while you may well be burned out, aphantasia is not a symptom of burnout.
"While burnout may influence health and can be a reason for people contacting health services, it is not itself classified by the WHO as a medical condition or mental disorder." -- https://en.wikipedia.org/wiki/Occupational_burnout
This also sounds like ADHD to me, not disassociation, but I could be wrong. See my other replies.
Also don't freak yourself out, reading a bunch of stuff on the web! It's easy to give oneself an anxiety attack trying to figure out things like this yourself. Instead write down your symptoms and see a doctor (first), psychologist, or psychiatrist.
OTOH if you mean the vague "mental health" of the HR or clickbait blog variety, then, yeah...