(Paraphrased from literature that I read at the time)
There's two kinds of burnout. One is caused by overwork, stress, long hours, not enough breaks, no holidays, not enough headcount, and so on. The kind of things this article talks about.
Instead, my burnout was caused by a lack of progress, which destroyed a lot of my other needs that I wasn't even thinking about. I felt no autonomy, no meaning to my work, and I felt out of place in the team because it seemed like I was the only one that was so bothered by it.
I wasn't working too much, and I often was only doing a few hours of work a day. However, because of organisational issues, I was making no progress, barely any improvements to the code, and was completely demotivated. I did try taking time off and taking it easy, as the traditional methods to combat burnout. Far from helping, they just made things worse, because that wasn't the problem. Looking back, the issue was a company pretending to care about Agile and just making everything worse in the process.
This ended up being a bit of a rambling vent, and I'm sorry about that - but my point is that we need to be aware that not all burnout is from stress and overwork. A lack of motivating factors can look the same as poor hygiene factors. Your reactionary measures *must* include actually talking to the person about what is causing the stress, and if needed, being willing to fix the organisational issues that are the root cause.