Check if content editor or script editor web part is present in the list forms (New/Display/Edit form) using PowerShell (CSOM/PnP)

This script will get all the editForm webparts and export it to a csv file. From there you can filter down for Script Editor and Content Editor Web Parts in the csv file. To get NewForm or DisplayForm update the script to look at DefaultNewFormUrl or DefaultDisplayFormUrl.

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue
 
#Configuration parameters
$SiteURL = "http://my.sharepoint.com"
$ReportOutput="C:\WebPartFormReport.csv"

$ResultCollection = @()
 
#Get All Subsites in a site collection and iterate through each
$Site = Get-SPSite $SiteURL

ForEach($Web in $Site.AllWebs)
{
    Write-host -f Yellow "Processing Site: "$Web.URL
  
    #Get all lists - Exclude Hidden System lists
    $ListCollection = $web.lists | Where-Object  { ($_.hidden -eq $false) -and ($_.IsSiteAssetsLibrary -eq $false)}

    ForEach ($list in $ListCollection) {
        $PagesLib = $Web.Lists[$list]

        # Get Default Edit form URL   (DefaultNewFormUrl, DefaultDisplayFormUrl)
        $form = $PagesLib.DefaultEditFormUrl
        $PageURL = $Web.site.Url+$form+"?DisplayMode=Design"

        $ASPXPage = $Web.GetFile($form)
                        
        $WebPartManager = $ASPXPage.GetLimitedWebPartManager([System.Web.UI.WebControls.WebParts.PersonalizationScope]::Shared)
                 
        #Get All Web Parts data
        foreach ($WebPart in $WebPartManager.WebParts)
        {
            $Result = New-Object PSObject
            $Result | Add-Member -type NoteProperty -name "Site URL" -value $web.Url
            $Result | Add-Member -type NoteProperty -name "Page URL" -value $PageURL
            $Result | Add-Member -type NoteProperty -name "Web Part Title" -value $WebPart.Title
            $Result | Add-Member -type NoteProperty -name "Web Part Type" -value $WebPart.GetType().ToString()
 
            $ResultCollection += $Result
        }
     }
}


#Export results to CSV
$ResultCollection | Export-csv $ReportOutput -notypeinformation

#References
https://www.sharepointdiary.com/2015/08/find-all-web-parts-in-use-in-sharepoint-using-powershell.html#ixzz78dD6sUlu
PowerShell to list all web parts used in the root default.aspx