Entity Detection Fails on Scaled Players (Using scale Attribute)

Expected behavior

When scaling a player (e.g., via a mod or plugin like SnC that modifies entity/player scale), combat interactions such as hitting or being hit should still function normally. Specifically, entity detection for attacks should align with the visible hitbox and properly register hits regardless of the entity's Y position or scale.

Observed/Actual behavior

When a player is scaled up using the "scale" attribute, combat detection becomes inconsistent. Hits often fail to register unless the player aims near the "feet" of the scaled entity. This issue does not occur on Fabric/Forge with the same setup — only on Spigot/Paper. It severely affects gameplay in scenarios involving large-scale entities (e.g., Titan shifters).

A side-by-side comparison video demonstrating the issue is available here
https://drive.google.com/file/d/1FGwJ0MITYNYZxQhFPLVzXYfP5tO1lWSb/view?usp=sharing

Steps/models to reproduce

I'm attaching a datapack where I trimmed the functions I'm using for my project, you need two players in order to test it. Instructions pop up once you enter the world

Damage.zip

Plugin and Datapack List

[21:58:16 INFO]: Bukkit Plugins:
[21:58:16 INFO]: - LuckPerms, Vault, VaultChatFormatter, WorldEdit

[21:58:51 INFO]: There are 5 data pack(s) enabled: [vanilla (built-in)], [file/bukkit (world)], [paper (built-in)], [file/Shingeki-no-Craft.zip (world)], [file/Damage.zip (world)

Paper version

[21:59:34 INFO]: This server is running Paper version 1.21.3-83-ver/1.21.3@d6c81da (2025-03-28T15:57:09Z) (Implementing API version 1.21.3-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.3-81-da71382 (MC: 1.21.3)

Other

No response

Start by reproducing the issue on Paper 1.21.3-83 with two players using the attached Damage.zip datapack, following the in-world instructions. Compare scaled-player hit detection with the visible hitbox and the Fabric/Forge behavior; done means attacks register consistently across the scaled entity rather than only near its feet.