light of the fire still on after the fire extinguishing

I was burning a forest of oak  with a flint and steel and the light that the fire emit was still there even when the fire was completely extinguished. I tried to update it by placing clock, but, sometimes, the light expand and sometimes not. I have taken some screenshots and it's not just a graphic bug, because the light level of the block is higher than 0. Also, my sky light is at 15 even though it's night time.