Banners are still discolored when viewing from certain angles

Duplicate of MC-163102. You even posted it on that issue. That one should be reopened and this should be closed as duplicate.

Not a duplicate of that ticket, as it only affects banners now. All the other blocks and items are fixed.

It still affects the top face of all blocks which make use of biome colours.

You're probably talking about MC-161841, which is a different issue that already exists for quite a while now.

Seem to be fixed in 19w44a.