The bug
When you splash invisibility on a horse, the saddle becomes invisible. When you do the same on a pig, the saddle stays visible. Note that this does not affect horse armor.
Splashing invisibility on a donkey or mule with a chest and/or saddle makes those equipped items invisible with the animal. This also affects saddled camels: MC-256469
Steps to Reproduce
Summon both a pig and a horse with a saddle:
/summon minecraft:pig ~4 ~ ~ {NoAI:1b,Saddle:1b} /summon minecraft:horse ~2 ~ ~ {NoAI:1b,Tame:1b,SaddleItem:{id:"minecraft:saddle",Count:1b}}Obtain a splash potion of invisibility and throw it at both entities.
Observed Behavior
Saddles on horses are not visible if horses have the invisibility effect, unlike pigs.
Expected Behavior
Saddles on horses would be visible when horses have the invisibility effect, just like the saddles of pigs are visible when they have the invisibility effect.
Linked issues
is duplicated by 6
MC-14007
Horse armor
Resolved
MC-16223
Invisible horses does not show their saddles/armor, and invisible donkeys does not show their saddle/chest.
Resolved
MC-29208
Found a bug, I think...
Resolved
MC-35246
Horse armor goes invisible with horse
Resolved
MC-64838
Horse saddles & armor affected by invisibility
Resolved
relates to 4
MC-224886
The chests of mules and donkeys flash red when the mob is damaged
Open
MC-61
endermen, spiders and cave spiders eyes and sheep wool remain visible when invisibility potion has been thrown on them
Resolved
MC-256469
Invisible camels don't show their saddles
Resolved
MCPE-17512
Horse armor not showing up when horse is under invisibly effect
Resolved
Attachments
Comments 34
Confirmed.
Invisible horses does not show their saddles/armor, and invisible donkeys does not show their saddle/chest.
What it should happen:
Horses with invisible potion effect should show their armor/saddle, also with donkeys, but with their chest/saddle.
What it happened:
Invisible horses/donkeys didn't show their armor/saddle/chest.
How to reproduce:
1) Spawn a horse/donkey.
2) Tame it.
3) Give the horse an armor, saddle it... In the case of donkeys, chest it, saddle it...
3) Throw an invisibility splash potion near the horse/donkey.
... Profit! The full horse/donkey with its armor/saddle/chest are invisible.
While this post misses out on the remainder of saddle/ride-able mobs, it is still present in 1.20.5 shown here in more detail: MC-271100 Specifically, this alternate bug includes the inconsistency shared by Llamas.
Can confirm, this issue is present in 1.21. As well as the additional rendering issues detailed in  MC-271100
gegy
it's a bug!😛