I was farming iron when I returned to the game in version 1.21 and the weather was a bit strange: my home biome is a forest, but the sun was setting and the sky started to shine like a storm and there was thunder in the sky. The sky was clear and in my home biome, forest, there were no rain particles. It was very strange and I believe it is a bug, since I have not seen any announcement of this type of addition to the game.

I was farming iron for about three hours before leaving the farm and going home; also, I updated the game from 1.20.5 straight to 1.21.