I have looked up if someone has already mentioned this, but I could find it. Not thay quickly, at least, and I'm not that familiar with this site yet... but ok, let's talk issues.

So, it was raining in the overworld. I was, however, in the savanna. The game knows to not show rain visuals here (except for the gray clouds) but, as it appears, doesn't know to consider the light level in the savanna biome the same as during normal day. It still thinks it is dark out, so the mobs I encountered like zombies and skeletons didn't burn and spiders were constantly hostile. I do have to note that there were some acacia trees and some village houses around, but they couldn't have provided major shade so it has to have been the daylight being weak. I'm pretty sure this is wrong and the sunlight should be just as strong as always during the day in these biomes, even if it's raining in other biomes.

I don't know if this might be intentional; if so, see this as a suggestion/feedback. I still labeled it as a bug though because that is my intentional guess.