If you have a light pack such as Cityz' lights (the example used here), you may have noticed this weird issue. Since it's with an Add-on, I figured it'd be best to post it here since it doesn't really belong in Help.
The main issue is that with shaders on, the default lights become absurdly bright, whereas without shaders they return to their non-shader softness. If I try to use a slightly dimmer version of the Player's Light, for instance, the light vanishes outright with shaders at minimum.

Default player's light with shaders at minimum.

Default player's light with shaders off.

Player's light dim with shaders at minimum.

Player's light dim with shaders off.
If someone could post an explanation, or preferably, a fix, that'd be nice. Thanks.