The movement speed attribute does not work correctly and disappears after re-entering the paper server

Expected behavior

When re-entering the paper server, the movement speed attribute is reset to the original value, while with the vanilla server core during testing there are no problems with resetting the movement speed attribute to the original. Please look into the cause and fix the bug.

Observed/Actual behavior

The speed attribute when entering a change in movement speed is reset on the paper server and does not save the current value of the movement speed on the ground

Steps/models to reproduce

didn't find

Plugin and Datapack List

Bukkit Plugins:
[13:31:01 INFO]: - AuthMe, Citizens, CMI, CMILib, DeluxeMenus, Interactions, PL-Hide, PlaceholderAPI, WorldEdit, WorldGuard

Paper version

This server is running Paper version 1.21.5-28-main@55f2020 (2025-04-22T20:12:27Z) (Implementing API version 1.21.5-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.5-26-d22644a (MC: 1.21.5)

Other

No response

The report names no source files, tests, or reproducible steps. Start by reproducing the movement-speed reset on Paper 1.21.5-28, first isolating it from the listed Bukkit plugins and comparing re-entry behavior with the vanilla server core. Done means identifying why the attribute is not retained and verifying that it resets correctly after re-entry.