Some blocks are not part of the #dragon_immune tag

Ender chests don't actually spawn in the end, only normal chests.
Aside from that, as Connor Steppie said, magenta stained glass; also banners generate in end cities.

They spawn in end cities. Also, they're made of obsidian so I'd say it's fitting anyway.

I looked at every structure file for end cities in 1.10 or so, and no update was given to them since, I don't remember any structure file containing ender chests.
On another note: End ships' brewing stand.

@FVbico, according to the Minecraft Wiki, ender chests do generate in end citites, starting in 15w31a.

https://minecraft.gamepedia.com/Ender_Chest#History

https://minecraft.gamepedia.com/End_cities#Structure

As of 1.16

Blocks which are related to obsidian are #dragon_immune (AKA: Crying obsidian + The respawn anchor)

So....

The rule that "It has to generate in the main end island" doesn't apply to those 2

So why shouldn't the ender chest be included if it is made of obsidian ?

+ All end city blocks (AKA : all the purpurs, chests, brewing stands, purple stained glass pane, banners, and end rods ) shouldn't be included in #Dragon_immune blocks 

Because they have no relation/materials to/from The Main End Island

Except for a couple

Which are the end stone bricks and it's variants

Because it is made of end stone

And end stone is #Dragon_immune

So they do go under the same category as the respawn anchor

I don't think it's really necessary to make purpur blocks and chorus blocks dragon-immune, but end stone bricks (+ slab, stairs, wall) and ender chest really should be dragon immune, since it's inconsistent with end stone and obsidian

Well, I think that Purpur blocks (and also shulker boxes) should be dragon inmune. Chorus plant blocks should also be inmune.

That's my opinion, and  many mapmakers would thank it, specially for battle arenas.

Can confirm in 21w03a.

Can confirm in 21w06a.

21w07a

Unfortunately all blocks except end stone bricks and dragon eggs are WAI per MC-85537 and MC-177521.

Can confirm in 21w13a.

Agreed with user-c84db, this issue should be edited to only contain dragon eggs and end stone bricks and its variants.

Can confirm in 1.17.1.

Can confirm in 21w37a.