The bug
When mousing over an advancement icon in the advancements menu, a dark overlay will be rendered over the advancements background and other advancements. This does not appear to be tied to a texture.
How to fix
Introduce a texture file for this darkness.
Linked issues
relates to 29
MC-278413
Chat background cannot be retextured
Open
MC-268805
panorama_overlay.png no longer works
Resolved
MC-268927
The dark background in inventory screens cannot be changed via resource packs
Resolved
MC-269079
Death screen background cannot be retextured
Resolved
MC-269364
Sign editing screen can no longer be retextured
Resolved
24 more links
Can confirm.