Blender Glossary definition of Blend Modes refers to GIMP docs on Layer Modes which defines Linear Light, and more, as

TODO

In contrast, Krita Blending Modes documentation defines Linear Light as:

Combines Linear Dodge and Linear Burn. When the lightness of the upper-pixel is higher than 0.5, it uses Linear Dodge, if not, Linear Burn to blend the pixels.

Linking Krita docs instead of GIMP docs would make the Blender Manual better, and is a easier to do than T76907.