azure devops release pipeline , bulk edit - powershell

Question

$Organization = "y"
$Project = "x"
$DefinitionID = "81"
$url = "https://dev.azure.com/$Organization/$Project/_apis/build/definitions/$DefinitionID?api-version=6.0"
Write-Host "URL: $url"
$pipeline = Invoke-RestMethod -Uri $url -Headers #{
Authorization = "Bearer $env:SYSTEM_ACCESSTOKEN"
}
Write-Host "Pipeline = $($pipeline | ConvertTo-Json -Depth 100)"
$pipeline.variables.v1030.value = "xyz"
####****************** update the modified object **************************
$json = #($pipeline) | ConvertTo-Json -Depth 99
$updatedef = Invoke-RestMethod -Uri $url -Method Put -Body $json -ContentType "application/json" -Headers #{Authorization = "Bearer $env:SYSTEM_ACCESSTOKEN"}
write-host "=========================================================="
Write-host "The value of Varialbe 'v1030' is updated to"
$updatedef.variables.v1030.value
error:
2022-03-17T13:05:24.9981259Z Invoke-RestMethod : {"$id":"1","innerException":null,"message":"Build pipeline
2022-03-17T13:05:24.9982421Z 81 was not found.","typeName":"Microsoft.TeamFoundation.Build.WebApi.Definition
2022-03-17T13:05:24.9982939Z NotFoundException, Microsoft.TeamFoundation.Build2.WebApi","typeKey":"Definitio
2022-03-17T13:05:24.9983313Z nNotFoundException","errorCode":0,"eventId":3000}
Hi I get this error in Logs,
I think I can not find the release pipeline number
The $ DefinitionID
I want to do it on 100 releases pipelines I'll wrap it with 'for' later, but first I want to see I can do on one