You have several problems/errors that I see in your log. I cannot say for sure which may be causing your issue. These are what I found:
1) You have several mods installed. Be sure to check with the mod authors to see if they have been updated to work with A20. Many times, mods can cause funny problems.
2) 2022-02-08T21:10:54 445.082 EXC Unable to write data to the transport connection: Eine vorhandene Verbindung wurde vom Remotehost geschlossen.
2022-02-08T21:10:54 445.110 ERR Exception in thread TelnetClient_167.94.138.61:51714:
2022-02-08T21:10:54 445.111 EXC The operation is not allowed on non-connected sockets.
at System.Net.Sockets.TcpClient.GetStream () [0x00036] in <6fcfdd162b5d4836bef3c96f53194db6>:0
at TelnetConnection.Close (System.Boolean kickedForLogins) [0x00021] in <d95321f623684130b4d3950a7292e611>:0
at TelnetConnection.ThreadEnd (ThreadManager+ThreadInfo _threadInfo, System.Boolean _exitForException) [0x00000] in <d95321f623684130b4d3950a7292e611>:0
at ThreadManager.myThreadInvoke (System.Object _threadInfo) [0x000ab] in <d95321f623684130b4d3950a7292e611>:0
UnityEngine.StackTraceUtility:ExtractStringFromException(Object)
Log:Exception(Exception)
ThreadManager:myThreadInvoke(Object)
System.Threading.QueueUserWorkItemCallback:System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
System.Threading.ThreadPoolWorkQueue

ispatch()
System.Threading._ThreadPoolWaitCallback

erformWaitCallback()
2022-02-08T21:10:54 445.111 INF Exited thread TelnetClient_167.94.138.61:51714
I am not familiar with issues with Telnet, most people don't use it as far as I know so we will need to wait for someone else with more understanding to address this. It might be that the port is not forwarded for Telnet to work properly.
3) 2022-02-08T21:24:29 1259.926 ERR [EAC] Log: [EAC Server] [Error] [21:24:29:735][Windows][EAC Server] [Err!][Cerberus] [Backend] Receive operation failed, disconnecting.
I am not familiar with this error either but I only saw this error once in your log, but right after that error, "Freddy" was disconnected.
4) 2022-02-08T21:37:35 2046.048 WRN No chunk for position 3467, 8, 2511, can not add childs to pos 3467, 8, 2512! Block cntMetalDesk02Closed
2022-02-08T21:37:38 2048.406 WRN No chunk for position 3471, 9, 2495, can not add childs to pos 3472, 9, 2495! Block cntMetalDesk02Open
This error makes me think that there are still A19 files still on your A20 server but again, we can wait for someone else to comment.
I see the point when players died but not why and I see that some vehicles are correctly saved in Vehicle Manager and I also see where the Vehicle Manager removed vehicles but it does not explain why.
My overall opinion, disable Telnet or be sure to forward the proper port which I believe is 8241. Also, if this is a private server for friends then disable EAC. EAC is anticheat software so hopefully you trust your friends plus with it disabled you will get a little better server performance. If I am correct and you do still have A19 files, this would require a server wipe and reinstall A20 only. However I would like to hear from someone else on my opinions to see if others agree or have better suggestions.