When a channel is deleted from a team in Microsoft Teams, Office 365 keeps that name in a reserved state for 30 days following the deletion. This means that if you create a new channel in that same team with the same name within those 30 days Nova Delegation & Policy Control (DPC) will show an error when it tries to get Office 365 to create the channel.
The message is:
Channel name already exists, please use a different name.
This is normal behaviour and means that the channel name is ‘in use’ for that 30 day period following the deletion.