Not stable power of engraving

Hello everyone. Last days was really hot outdoor and in my workroom but i not worked then so long. The water temperature never rise more than 25C. My machine have reci w1 about 80w tube, bought 6 months ago. I have problem with engraving, photos attached. Its look like the power is not stable and waves, dropping down. I engraved laminates with 12% power always and works well. Today 12% power is not enough and laser cant burn first layer of material. I tried with 17% and looks better but its not perfect job. I dont know where is problem becouse cutting 5mm acrylic is no problem.

Any ideas? I chcked accuracy, the mirrors and len, all clear.