(Java Minecraft 1.14) Unable to give player custom potion with Harming 4?

I'm trying to make a Holy Hand Grenade type of splash potion which has instant harming 4. I have

give @s minecraft:splash_potion{CustomPotionEffects:{id:7,Amplifier:3,ShowParticles:0},Enchantments:[{id:"minecraft:multishot",lvl:1}],display:{Name:"{\"text\":\"Holy Hand Grenade of Antioch\",\"color\":\"gold\"}"}} 2

and I followed the wiki in adding the tags, but for some reason it doesn't even have harming, it only has uncraftable potion.

A) What am I doing wrong to not get the harming effect at all?

B) Is it possible to get harming 4? If it is, how can I?

CustomPotionEffects is a list, so everything in it has to be put into square brackets ([]).

And for some reason custom potion effects, as the only place in the game, require "Id" with a capital "I/i". Note that the non-capital "id" is indeed correct for the enchantments.

Putting these two corrections together, the correct command should be:

give @s minecraft:splash_potion{CustomPotionEffects:[{Id:7,Amplifier:3,ShowParticles:0}],Enchantments:[{id:"minecraft:multishot",lvl:1}],display:{Name:"{\"text\":\"Holy Hand Grenade of Antioch\",\"color\":\"gold\"}"}} 2

Source: I always start at "chunk format" as the central hub for everything, because I'm lazy, which directs me to "Player.dat#Item structure", specifically to Potion effects (archive).