Custom potions lose NBT after brewing

Can confirm that this issue is still present in 21w05b. You can use the following command to reproduce this issue:

/give @s minecraft:potion{Potion:"minecraft:strength",CustomPotionEffects:[{Id:14b,Amplifier:0b,Duration:1200,Ambient:0b,ShowParticles:1b,ShowIcon:1b}],CustomPotionColor:255}

Thanks to @unknown, for providing the command.

Thanks, I have included the command in the description.

@@unknown, what do you mean by "adding ingredients in a crafting table"?

after adding ingredients in a brewing table or crafting

In case you mean crafting tipped arrows, that seems to preserve the custom effects in 21w05b.

Can confirm in 21w06a.

Can confirm in 1.16.5 and 21w08b.

Can confirm in 21w15a.

Can confirm in 1.18.2 and 22w18a.

Can confirm in 23w33a.

This is still an issue in 24w11a. But, if a potion just has minecraft:potion_contents.custom_effects, without setting minecraft:potion_contents.potion, it will now simply fail to brew altogether instead of converting to an uncraftable potion as before.

(It will, however, still attempt to brew into a new potion, thus wasting potion ingredients, but that's a whole other issue entirely.)

Can confirm in 1.21.8.

This issue contrasts the crafting of tipped arrows. Tipped arrows can be crafted with custom potions and yield the expected result: a custom tipped arrow.

You can turn a custom lingering potion into custom tipped arrows, but not a custom splash potion into a custom lingering potion.