I started to notice that I was getting very tired at work. Literally everything has stopped pleasing me there and any new task only irritates me. I'm holding on, but literally from the last possible effort. Productivity is at zero. What do I do?
How I understand you. I was in a similar situation myself. It all led to a real nervous breakdown. I ended up having to quit my job and I haven't worked anywhere in over a year.
You can't put yourself in that state. Do not bring yourself to burnout - it's dangerous. And you shouldn't hope that everything will somehow normalize itself. It won't. So my advice to you is to study some productivity tips here: https://www.voiset.io/category/tips-for-productivity This will help you understand your problem and how to deal with it.