What are the disadvantages of Unity3D?

The disadvantages of Unity3D are: performance limitations, particularly for high-end graphics or complex games, as Unity may not match the rendering capabilities of engines like Unreal Engine. Projects made with Unity3D generally give larger-sized results, which can affect the app’s performance, especially for mobile apps. Unity’s Pro and Enterprise licensing may be costly for some developers.
This wide feature set and Unity interface becomes a little difficult to grasp for beginners. Sometimes, complicated advanced graphics are done in Unity by writing custom scripts or using third-party plugins, which complicates the development process even more.