How to make a request correctly:

1. Mod name
2. Screenshots/videos showing the bug
3. If the bug requires some steps to reproduce (take {a}, put in {b}, press {c}, done), provide those too (Optional, if the bug can be reproduced when interacting with 1/2 item or block. That is, it doesn't require anything complicated)

Fix lighting bug with psychedelicraft:

Go to the path .minecraft\config\psychedelicraft.cfg, in this file find

# Whether 3D shaders are enabled - disabling them will disable drug visuals, but also fix graphical glitches.
B:shaderEnabled=true

and set the value B:shaderEnabled=false. This will fix the "Lighting bug" problem when using psychedelicraft