The current spec does not clearly indicate what should be done with color values that land outside of the standard dynamic range gamut of the screen (colors that, when converted to the color space of the screen, land outside of the [0, 1] interval).

The following proposal indicates a default behavior (that matches existing implementations and WebGPU's default behavior), and provides a mechanism for opting in to extended-range brightness.
https://github.com/ccameron-chromium/webgl-hdr/blob/master/EXPLAINER.md