This has been referenced in Reddit threads; but a target currently on fire, or standing in a flames should no longer be obscured by shadow with a penalty to hit. This increases tactical options.
Maybe some underdark creatures should have a penalty to hit when encountering strong light sources?
Agree with both, unfortunately I can only find sunlight sensitivity mentioned in 5e, not bright light sensitivity. Drow and Duergar have this, would expect other Underdark races to be the same. (I guess our tadpoles protect us?)
Something I would like to see that goes along with this is if the party has bright light (torches, dipping candles, etc) while in a dark area, then enemies that would normally have the penalty to hit should now have a normal chance.