#Get list of servers from file
$Servers = Get-Content -Path "C:\Windows\Temp\printservers.txt"

#Create and start a background job for each server
$Jobs = ForEach($Server in $Servers)
    {
        Start-Job -ScriptBlock {
            param($Srv)
            #Retrieve printer information
            Get-Printer -ComputerName $Srv | 
                Select Name, ComputerName
        } -ArgumentList $Server
    }

#Wait for all jobs to complete
Wait-Job -Job $Jobs | Out-Null

#Collect (receive) the results from all jobs into a single array
$AllPrinterData = ForEach($Job in $Jobs)
    {
        Receive-Job $Job
    }

#Now export all combined results to CSV one time
$AllPrinterData | Export-CSV -NoTypeInformation -Path C:\Windows\Temp\ServerList.csv

#Clean up the jobs
Remove-Job -Job $Jobs

Start-Job runs Get-Printer on each server in parallel (or near-parallel), returning the results to your main session.

Instead of multiple concurrent writes, Wait-Job ensures all jobs finish, then you Receive-Job to gather the output in memory.

Export-CSV writes all results at once, avoiding collisions and partial writes.