End portal frames emit a light level of 1

The bug

End portal frame blocks emit a light level of 1.

Aside from this making them very impractical as a light source, it also causes visual problems such as MC-50734, which results in ugly and sharp lighting transitions to other blocks due to light-emitting blocks ignoring ambient occlusion. Removing the light emitted by end portal frames, which would make effectively zero changes to gameplay, would very likely alleviate this bug.

How to reproduce

1. Place an end portal frame block in a completely dark area

2. Stand on this end portal frame block

3. Open F3

Expected results

The debug screen would report a block light level of 0.

Actual results

The debug screen reports a block light level of 1, which can be very easily attributed to the end portal frame.