The bug

The darkness effect which can be seen around the edges of the screen under certain circumstances will be hidden if the player presses F1.

Whether or not this is intended is unclear, as many other tickets in this vein have been either fixed or considered intentional; input from Mojang is needed on this matter. The following list is of tickets involving similar effects that disappear(ed) with F1 and their resolutions:

• MC-197123: world border redness - currently open but triaged, implying unintended
• MC-196469: nausea green tint - was fixed
• MC-83353: nether portal overlay - considered intentional
• MC-121536: carved pumpkin overlay - considered intentional
• MC-203575: spyglass overlay - considered intentional
• MC-205029: powder snow overlay - considered intentional

How to reproduce

1. Enter a dark area, such as a cave
2. Press F1
   1. Note that the scene becomes slightly brighter overall, especially at the corners of the screen

Expected results

Pressing F1 would have no bearing on this dark vignette effect.

Actual results

F1 shows or hides this effect.