Chunks in new chunk system unloaded instantly when player died, ignoring delay-chunk-unloads-by option

Expected behavior

The chunk unload time is not instant and should follow the delay-chunk-unloads-by option.

Observed/Actual behavior

I used a weird method to find out the issue. Our server also have mythicmobs installed, and I set the mobs to only despawn when chunk unloads.

I first tried paper 1.19.2 build 307 (new chunk system). I spawn a mm mob, and let the mob kill me (so i return to spawn), and immediately I return to the death location using /back. The mob despawned. I also try this near server spawn (chunks near spawn are always loaded), and the mob did not despawn.
After that I tried 1.19.2 build 172 (old chunk system). Using the same method above, the mm mob did not despawn.

I also tried refreshing configurations, removing all other plugins in the new chunk system, but everytime the mob will despawn outside the loaded spawn chunks.

from these information, I think that in the new chunk system (build 307), the chunks are unloaded instantly (less than 2 sec) after player death, and the mm mobs despawned instantly due to chunk unload. But in the paper per world config, I set the delay-chunk-unloads-by to 30s.

Steps/models to reproduce

As described in the above section.

Plugin and Datapack List

AdvancedPortals, AuctionHouse, BetterRTP, BungeeTabListPlus, ChatItem, ChestCleaner, ChestShop, Chunky, Citizens, CMILib, ConsoleSpamFix, CoreProtect, DeluxeMenus, DeluxeTags, DiscordSRV, dtlTradersPlus, DungeonParties, Essentials, EssentialsAntiBuild, EssentialsChat, EssentialsProtect, EssentialsSpawn, EvenMoreFish, ExcellentCrates, ExecutableItems, FastAsyncWorldEdit (WorldEdit), FlightControl, GadgetsMenu, GriefDefender, GSit, Guilds, Gunging_Ootilities_Plugin, Hat, HeadDatabase, HolographicDisplays, IllegalStack, Images, LibsDisguises, Lift, Lottery, LuckPerms, MarriageMaster, MessageAnnouncer, Minepacks, MMOCore, MMOItems, ModelEngine, Multiverse-Core, Multiverse-NetherPortals, MysqlEconomyBank, MythicDungeons, MythicLib, MythicMobs, NametagEdit, NexEngine, PacketListenerApi, PlaceholderAPI, PlayerPoints, Playtimes*, ProtocolLib, Referral, SCore, ServerTutorialPlus*, Stocks*, SuperVanish, TimeIsMoney, TitleManager, Vault, Votifier, WorldGuard, WorldGuardExtraFlags

Paper version

This server is running Paper version git-Paper-307 (MC: 1.19.2) (Implementing API version 1.19.2-R0.1-SNAPSHOT) (Git: 476ef25)
You are running the latest version
Previous version: git-Paper-173 (MC: 1.19.2)

Other

No response

Start by reproducing the report on Paper 1.19.2 build 307 with delay-chunk-unloads-by set to 30 seconds, comparing player death and return to the death location with the older chunk system. Investigate the new chunk system's unload behavior; done means chunks do not unload instantly after death and the configured delay is respected. Pull request #9519 is linked and closed.