Why do I need witness in WSFC with two nodes? I have Windows Server 2019 and SQL Server 2019 running in both nodes of my cluster. In my case everything is working fine without witness. I need Windows Server Failover Clustering (WSFC) for availability group which I'm using as DR solution.

When both nodes are running, I'm shutting down one node (which has primary database of my AG) and do failover of Availability group from another and vice-versa.  Can someone please explain why we need a witness in two node failover cluster or how can I recreate that scenario in which we'll need a witness.
Straight from the docs, with a two-node cluster without a witness:


  One node's vote is zeroed, so the majority vote is determined out of a
  total of 1 vote. If the non-voting node goes down unexpectedly, the
  survivor has 1/1 and the cluster survives. If the voting node goes
  down unexpectedly, the survivor has 0/1 and the cluster goes down. If
  the voting node is gracefully powered down, the vote is transferred to
  the other node, and the cluster survives. This is why it's critical to
  configure a witness.


Understanding cluster and pool quorum

And you can simply use Cloud Witness, so you don't need a shared disk, third node, or file share.