The following crash occurred. I am unable to see a reference of any plugin under this. At the time, one player was building a house and the other was growing fungi with bonemeal.

[20:30:11] [Spigot Watchdog Thread/ERROR]: The server has stopped responding! This is (probably) not a Spigot bug.
[20:30:11] [Spigot Watchdog Thread/ERROR]: If you see a plugin in the Server thread dump below, then please report it to that author
[20:30:11] [Spigot Watchdog Thread/ERROR]: Especially if it looks like HTTP or MySQL operations are occurring
[20:30:11] [Spigot Watchdog Thread/ERROR]: If you see a world save or edit, then it means you did far more than your server can handle at once
[20:30:11] [Spigot Watchdog Thread/ERROR]: If this is the case, consider increasing timeout-time in spigot.yml but note that this will replace the crash with LARGE lag spikes
[20:30:11] [Spigot Watchdog Thread/ERROR]: If you are unsure or still think this is a Spigot bug, please report to https://www.spigotmc.org/
[20:30:11] [Spigot Watchdog Thread/ERROR]: Be sure to include ALL relevant console errors and Minecraft crash reports
[20:30:11] [Spigot Watchdog Thread/ERROR]: Spigot version: 3009-Spigot-73fb609-d97d918 (MC: 1.16.5)
[20:30:11] [Spigot Watchdog Thread/ERROR]: ------------------------------
[20:30:11] [Spigot Watchdog Thread/ERROR]: Server thread dump (Look for plugins here before reporting to Spigot!):
[20:30:11] [Spigot Watchdog Thread/ERROR]: ------------------------------
[20:30:11] [Spigot Watchdog Thread/ERROR]: Current Thread: Server thread
[20:30:11] [Spigot Watchdog Thread/ERROR]: PID: 30 | Suspended: false | Native: false | State: WAITING
[20:30:11] [Spigot Watchdog Thread/ERROR]: Stack:
[20:30:11] [Spigot Watchdog Thread/ERROR]: sun.misc.Unsafe.park(Native Method)
[20:30:11] [Spigot Watchdog Thread/ERROR]: java.util.concurrent.locks.LockSupport.park(Unknown Source)
[20:30:11] [Spigot Watchdog Thread/ERROR]: com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:471)
[20:30:11] [Spigot Watchdog Thread/ERROR]: com.google.common.util.concurrent.AbstractFuture$TrustedFuture.get(AbstractFuture.java:78)
[20:30:12] [Spigot Watchdog Thread/ERROR]: sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
[20:30:12] [Spigot Watchdog Thread/ERROR]: sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source)
[20:30:12] [Spigot Watchdog Thread/ERROR]: sun.nio.ch.SelectorImpl.select(Unknown Source)
[20:30:12] [Spigot Watchdog Thread/ERROR]: io.netty.channel.nio.SelectedSelectionKeySetSelector.select(SelectedSelectionKeySetSelector.java:62)
[20:30:12] [Spigot Watchdog Thread/ERROR]: Stack:
[20:30:12] [Spigot Watchdog Thread/ERROR]: java.lang.Object.wait(Native Method)
[20:30:12] [Spigot Watchdog Thread/ERROR]: java.lang.Object.wait(Unknown Source)
[20:30:12] [Spigot Watchdog Thread/ERROR]: java.lang.ref.Reference.tryHandlePending(Unknown Source)
[20:30:12] [Spigot Watchdog Thread/ERROR]: java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)
[20:30:12] [Spigot Watchdog Thread/ERROR]: ------------------------------

The list of plugins is:

BestTools
AngelChest
WildStacker
ProtocolLib
ChestSort
mineOres
Vault
NetherEnableWater
EnhancedEnchants
CustomTime
ArmoredElytra
Drop2Inventory
MobTools
Coordinates
ChopChop
Cartographer2