Nutrient burn?

On one of my plants, on two of the top buds the end of the leaf tips are dead and curling up. you can see in the pics the two different buds. There are a few tips turning yellow on other parts of the plant too. And some of the fan leaves have little yellow dots.

Is this nutrient burn? They're 8 weeks old and a week or so from harvest, Im about to flush the plants and feed them plain water anyway. But if its not nutrient burn i should probably know what it is.

I think you already know what's going on and you are taking the right steps to remedy the problem.

That is common towards the end of budding cycle if i did my research correctly.