For me a true sense of "I am burned out" is like a recession. You don't see it coming but you can look back 6 months and realize "oh shit I'm deep in very bad burnout".

For me it was a deep dissatisfaction with the work I was doing. This was caused by doing work that had no meaningful purpose, and also the people who were controlling what work I did were not giving me any autonomy or say in what was happening so I felt very powerless and my work was deeply unfulfilling.

It was multiple jobs where it was a bad fit, and I tried to force it and "make it work" because you have to get paid to live. For me burnout is a symptom of a sick society and unfortunately you can't just treat the individual its the societal conditions that cause the pain. The burnout and depression is a natural and reasonable reaction to the unpleasant experiences.

I would suggest changing jobs if you:

1. Lack friends / coworkers you can depend on 2. Feel like your work is not meaningfully contributing 3. Feel like your voice is not welcome or heard 4. Cannot find joy or happiness in tasks or hobbies you once enjoyed (outside of work) 5. Find yourself getting angry / snapping / losing temper over trivial non-important things either at work or at home.