This PowerShell script lists out how to use Az CLI's DevOps extension to walk through the release definitions in a project and check for a specific taskId.

azDevopsReleaseTaskAudit.ps1

# Set the PAT as an Environment variable, put this in your profile.
# I only use the CLI for read operations so make sure you grant the PAT only that access
$env:AZURE_DEVOPS_EXT_PAT = "<Insert PAT Token here>"

# configure the defaults for the Az DevOps extension for Az CLI to use
az devops configure --defaults organization=https://dev.azure.com/dexterposh project=Test.Project

# see the configured defaults
az devops configure --list

# fetch all the release pipelines metadata for the project
$ProjectName = 'Test.Project'

# Explore one of the Task Release definition to fetch the taskID
# Create or reference an existing Release definition containing the task you want to look for
# In my case, I created a new pipeline only with AzSK_SVTs task
$dummyReleaseDef = az pipelines release definition show --name test-pipeline-with-azsk | ConvertFrom-Json

# Now check the task Id in the
$dummyReleaseDef.environments.deployphases.workflowtasks | Select-Object -Property name, taskId, enabled 

# From the above I derived that the taskID for AzSK_SVTs is the below
$TaskID = "c016cc55-9914-4a9c-b9df-f24d6f9a40f6"

# make a note here that we query the release definition list
$ReleaseDefs = az pipelines release definition list --project $ProjectName | ConvertFrom-Json

# Generate output
$AzSKTaskReleaseAudit = foreach ($releaseDef in $ReleaseDefs)
{
    # fetch the full Release definition Object for the Release def
    $releaseDefObject = az pipelines release definition show --id $releaseDef.Id | ConvertFrom-Json

    # Filter the workflow tasks across environments & deploy phases to see the task is present
    # Note how I use taskID instead of task name
    $AzSKTaskFound = $releaseDefObject.environments.deployphases.workflowtasks |
        Where-Object -Property taskId -eq $TaskID

    # generate the Output
    if ($AzSKTaskFound)
    {
        [PSCustomObject]@{
            ReleaseName     = $releaseDefObject.Name
            ReleaseId       = $releaseDefObject.Id
            AzSKTask        = $true
            AzSKTaskEnabled = @($AzSKTaskFound.Enabled)
        }
    }
    else
    {
        [PSCustomObject]@{
            ReleaseName     = $releaseDefObject.Name
            ReleaseId       = $releaseDefObject.Id
            AzSKTask        = $false
            AzSKTaskEnabled = @($false)
        }
    }
}

# Analyze the resuls
$AzSKTaskReleaseAudit