Import items from a CSV file to a Sharepoint Online list

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as you make use of CSOM and SharePoint Online Management shell, I`d suggest to download the latest CSOM libraries from here:
https://www.nuget.org/packages/Microsoft.SharePointOnline.CSOM

and once downloaded load them into your current session.
The installed ones you are adding currently might not be compatible with SharePoint Online.

BTW. , you do not need to install those, they could be filed relative to the scripts´ location as well.
e.g. this is a shortened function I would use.

function get-assemblies {
   $sCSOMPath= $scriptDir       
        $sCSOMRuntimePath=$sCSOMPath +  "\Microsoft.SharePoint.Client.Runtime.dll"         
        $sCSOMClientPath=$sCSOMPath +  "\Microsoft.SharePoint.Client.dll" 
        #$sCSOMUploadPath= $sCSOMPath +" \Microsoft.SharePoint.Client.Publishing.dll"
            #Load SharePoint Online CSOM Assemblies 
            try{         
                Add-Type -Path $sCSOMClientPath     | out-null
                Add-Type -Path $sCSOMRuntimePath    | out-null
              }
            catch {
                Add-LogEntry $logFilePath  $requestNumber  $env:hostname 'error' "failed loading assemblies"
                return Get-JsonStatus 1 "required dlls for SharePoint on $env:computername not found."
                 }
}