Add-PnPFieldFromXml -List $ListName -FieldXml $mySchemaXML Error

[LouFarho]

I have a PnP PowerShell script I have used successfully for some time. It has been a few months since I last used it so I do not know when it last worked.

Background:
I have a script I use to export the custom fields of a list. This was due to migrations from SP2019 and poor naming of list fields. For select scenarios, I would recreate the list from scratch.
I would export the custom fields from a list using this snippet:

foreach($field in $ListFields){
    $($field.Title + "," + $field.InternalName + "," + $field.TypeDisplayName + "," + $field.SchemaXml) >> $OutputFile
}

The csv file would have the internal names cleaned up leveraging find/replace.

Once I have the fields cleaned up, I run a PnP script to run thru the fields in the CSV.

Bug:
When the script runs currently, it is throwing an error when executing this statement:
Add-PnPFieldFromXml -List $ListName -FieldXml $xml
throws the following error:
Unexpected response from the server. The content type of the response is "text/plain; charset=utf-8". The status code is "NotFound".

Get-PnpException provides the following:

Message          : Unexpected response from the server. The content type of the response is "text/plain; charset=utf-8". The status code is 
                   "NotFound".
Stacktrace       :    at PnP.PowerShell.Commands.Base.PnPConnectedCmdlet.ProcessRecord()
                      at PnP.PowerShell.Commands.PnPSharePointCmdlet.ProcessRecord()
                      at System.Management.Automation.CommandProcessor.ProcessRecord()
ScriptLineNumber : 9

I looked up the command from here to verify nothing had changed https://pnp.github.io/powershell/cmdlets/Add-PnPFieldFromXml.html
On this page, there is an example to run:

$xml = '<Field Type="Text" Name="PSCmdletTest" DisplayName="PSCmdletTest" ID="{27d81055-f208-41c9-a976-61c5473eed4a}" Group="Test" Required="FALSE" StaticName="PSCmdletTest" />'
Add-PnPFieldFromXml -List "Demo List" -FieldXml $xml

I executed the above for my site's list and got the same error.

I also checked to make sure I am on the latest release: 3.1.0 by running the command to update it.

Update-Module PnP.Powershell -Scope CurrentUser

Thanks!