When summoning a firework using the command:
/summon FireworksRocketEntity ~ ~10 ~ {Motion:[0.0,1.0,0.0],LifeTime:0,FireworksItem:{id:"minecraft:fireworks",Count:1b,tag:{Fireworks:{Flight:1b,Explosions:[

{Flicker:1,Trail:1,Type:4,Colors:[16711680,16747520],FadeColors:[5263440,0]}

]}}},Life:1}
The fadecolor from red and orange to black and gray should be a gradient fade, but instead only the very ends of the trails are the black and gray colors. The trails do not turn gradient into the appropriate colors as it did in previous versions.

As you can see in the picture, the firework is being set off, and the red/orange did not fade, however the particles are visible on the ends of the trails.