black dot

Today I've woke up to this black dot on my ASUS VE278Q, I know that It cannot be fixed but I've been wondering what can cause it? Nothing even touched monitor or has been spilled over it. I've been thinking, over the night during the thunder I've pulled out my cables from the wall and plugged...

So this is the third time that this has happened I believe and the spot is totally random. I think it is probably some sort of software problem because it does actually show up in screenshots so it can not be a dead pixel. I can also cover it up if i put my mouse over it. I don't really know how...