I just tested it on my server. I found the issue, and there was certainly an error.
12:53 [Error] Failed to call hook 'OnPlayerDeath' on plugin 'SurvivalArena v1.0.29' (KeyNotFoundException: The given key '0' was not present in the dictionary.)
at System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) [0x0001e] in <de920293e401402ab375ad8a2e1b19da>:0
at Oxide.Plugins.SurvivalArena.CheckWin () [0x00037] in <29f058a994f24c408140cafe8d1e6b64>:0
at Oxide.Plugins.SurvivalArena.LeaveEvent (BasePlayer player, System.Boolean died, System.Boolean event_ended) [0x00269] in <29f058a994f24c408140cafe8d1e6b64>:0
at Oxide.Plugins.SurvivalArena.OnPlayerDeath (BasePlayer player, HitInfo info) [0x00106] in <29f058a994f24c408140cafe8d1e6b64>:0
at Oxide.Plugins.SurvivalArena.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x02b9f] in <29f058a994f24c408140cafe8d1e6b64>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <8cb2d664f1574f2b96d53f1c1869d96a>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <8cb2d664f1574f2b96d53f1c1869d96a>:0
I have posted it on my discord for testing to see if this resolves the issue.