This didn't happen when the update, 1.16.10 was released, at least not yet. I was just playing my survival world when I had gone to the Nether to get lava buckets. I came back, and I saw SO MANY LIGHTING GLITCHES. I thought, maybe this was a rare occurrence because I thought that they had fixed this in an update that was released a year ago. It happened each and every time I went to the Nether and back. Each time it got worse too. The area around most of my torches were darkened. I could fix this by breaking and placing the torch back into it’s original position, but if I did the same thing again (going to the nether and back into the overworld) it would appear again. It became very frustrating, I’m sure Mojang will fix it though. 

Summary: When traveling from the Nether into the Overworld, I experienced many lighting glitches where areas around torches would be darkened, I could fix this each time temporarily by breaking the torch, and placing it again.