I just noticed that the beacon block has no shading in the inventory. Pictures down for proof:
And steps to reproduce:
1 Grab a beacon and put it in your inventory.
2 Look at it. The shading+contrast is turned off on the beacon, however it retains them when the beacon is placed, so it only affects the preview render inventory.
Duplicate of MC-48435 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.