The texture in unreal engine is too bright and I don't fully understand why and when this is the case. Here is a good example that shows the issue:

https://forums.unrealengine.com/t/character-texture-and-rendering-looks-way-different-in-ue4/457605

In character creator, the textures seem fine, but in unreal, suddenly the textures look widely different. Increasing the AO strength seems to improve the situation in my case, but I am not sure whether this is the actual cause of the problem.