I can confirm for 1.17. Why won't you fix it?
I recently added Christmas chests for donkeys/mules/horses in my mod: https://www.curseforge.com/minecraft/mc-mods/better-christmas-chests
and yes I was surprised when I found out the horse textures also have chests even thought they can't be equipped
My mod Better Christmas Chests fixes this issue: https://www.curseforge.com/minecraft/mc-mods/better-christmas-chests
My mod Better Christmas Chests fixes this issue: https://www.curseforge.com/minecraft/mc-mods/better-christmas-chests
Also minecart with chest items don't use the chrismas chest texture but the minecart with chest entity does
Yes it is but the other issue didn't show up when I searched for skyglass so I created a new one.
I don't believe the issue for ender chests is fixed as one of the devs purposefully added the functionality for enderchests to get gift wrapped. A better fix would be to just draw a purple present to match the with the existing gift texture.
Also trapped chests still use an identical texture to normal chests making it impossible to tell the difference. A previous bug report was fixed by making the trapped chest have the gift wrapped texture but using the same identical texture just doesn't work.
Also the chest minecart still uses the default texture and never shows gift wrapping.
I know these are probably just QoL fixes and you have more important things to worry about but this has been open for ages and you have only half fixed it. And in my opinion that fix made it worse.