Problem in the scene loading – the downloaded scene is dark:

Although it is intended to be like this (launched immediately from this scene, and not through the initial):

is usually loaded using:

scenemanager.loadscene ("Main");

What is it connected with and how can this be fixed?

Answer 1, Authority 100%

This is a jag bug, try to get a knitting project and everything will be normal there. I came across the same problem when I worked with a 3D application.
Fixyl, it seems, with the help of shutdown auto-generation of light in the project lighting settings.