Fishing rod passes through/bounces off Ender Dragon
Created Issue:
Enderdragon can't get hit by a fishing rod
If you try to attack the Ender dragon with a fishing rod, it will do nothing.
Changed Description:
If you try to attack the Ender dragon with a fishing rod,
it will do nothing.If you try to attack the Ender dragon with a fishing rod, the fishing rod will just pass into it.
Changed Summary:
Enderdragoncan't gethit byafishingrodEnderdragon don't get effect by fishind rod
Changed Summary:
Enderdragon don't get effect by fishind rodFishing rod pass threw Enderdragon
Changed Summary:
Fishing rod pass threwEnderdragonFishing rod pass through Enderdragon
Changed Description:
If you try to attack the Ender dragon with a fishing rod, the fishing rod will just pass
intoit.If you try to attack the Ender dragon with a fishing rod, the fishing rod will just pass through it
Changed Description:
Added Affects Versions: 1.12.2
Added Mojang Priority: Normal
Changed Summary:
Fishing rod passes through/bounces off Enderdragon
Added Affects Versions: 20w07a
Added Affects Versions: 20w51a
Added Affects Versions: 21w03a
Added Affects Versions: 21w05b
Added Affects Versions: 21w06a
Added Attachments:
Changed Summary:
Fishing rod passes through/bounces off EnderdragonFishing rod passes through/bounces off Ender Dragon
Added Attachments:
Added Affects Versions: 1.17.1
Added Affects Versions: 1.18.2
Added Affects Versions: 1.19
Added Affects Versions: 1.19.2
Removed Category: (Unassigned)
Added Affects Versions: 1.19.3

Still waiting for a comment.
I know the enderdragon's collision box doesn't exactly work. It may be the hook is looking for a collision box rather than a hitbox. Either that or you're missing the hitbox entirely
Nope, I tried in everyplace and still the fishing rod is passing through the dragon.
For me it seems to hit the Enderdragon's hitbox but just bounce to the floor (in 1.12.2).
Can confirm that this issue is still present in 20w51a. The fishing bobber simply passes through the ender dragon.
Can confirm in 21w03a.
Can confirm in 21w05b.
Can confirm in 21w06a.
Can confirm in 1.16.5 and 21w08b.
Video attached.
This ticket is currently blocked by
MC-219849.Can confirm in 1.17.1.
Can confirm in 1.18.2.
Can confirm in 1.19.
Can confirm in 1.19.2.