Web browsers don't handle gamma blending correctly.

Consider a simple image with red, green, blue areas: rgb(127, 0, 0), rgb(0, 127, 0), rgb(0, 0, 127)

Apply a simple blur filter: style="filter: blur(10px)"

Your browser probably (incorrectly) rendered the area between the colors with odd black bars:

The correct rendering is actually:

This happens because your browser (GPU) is naïvely blending together gamma-compressed colors as though they are on a linear scale.

With non-linear gamma rgb(127, 0, 0) is not halfway (127 / 256) between between rgb(0, 0, 0) ('blackest red') and rgb(255, 0, 0)('reddest red'). Doing naïve averaging (blurring) of color values this way leads to rgb color values that are darker than intended.

As the web moves to content with more than just sRGB color, the mess causes by incorrectly blending gamma-compressed colors will probably worsen.