Burn out and brain fog all the time

Is it possibile to be in burn out while doing nothing? It’s exam season for me, and I can’t literally study, when I try to my brain is completely empty and I cannot focus and understand, I have no motivation
I realised that I also feel brain fog even when I’m not studying like when I play games I feel the same way
I don’t understand why this happens because in hight school I could stay behind studying, had motivation, even though I didn’t have the greatest grades and didn’t spend all day studying, but still I never experienced anything like this, and this started since I started uni