The decay is the same (physically-based) but the units of light strength are different. Though perhaps rendering to linear images and skipping Blender’s view transform helps here.
However, when adding an outline pass to the composer (as indicated in the PR), the scaling becomes active again but the scene suddenly becomes too dark.
You mean OutputPass, correct? Are there any other effects in the stack? If you had other effects then presumably they’ll need to come after OutputPass to match what you did before. But that isn’t usually what you want, most effects should come before tone-mapping, see Different color output when rendering to WebGLRenderTarget - #7 by donmccurdy for more on that.