Town-Zone altering effects reoccuring

So while I was in act 2 and were at the last quest (when it turns dark because of the Vaal Oversoul) the town constantly switches between normal and dark.

Same happens in act 7. Because Doedre is alive the town is green. After killing her it is normal (yellow-ish). But again the game cycles through these effects.

https://imgur.com/a/yIiyuYi