Fatal error: Uncaught Error: Call to undefined function imagecreatefromjpeg()

Just starting a new thread on this as I was more than beginning to hijack the other thread!

I'm getting this error when I attempt to upload an image via MySQLi Insert Record and File Manipulation Upload Wizard:

Fatal error: Uncaught Error: Call to undefined function imagecreatefromjpeg() in C:\inetpub\wwwroot\tammyssweetstems\webassist\file_manipulation\helperphp.php:962 Stack trace: #0 C:\inetpub\wwwroot\tammyssweetstems\webassist\file_manipulation\helperphp.php(174): WA_DFP_ResizeImage() #1 C:\inetpub\wwwroot\tammyssweetstems\njadmin\add_banner.php(78): WA_DFP_UploadFiles() #2 {main} thrown in C:\inetpub\wwwroot\tammyssweetstems\webassist\file_manipulation\helperphp.php on line 962

Is this definitely related to not having GD installed in PHP?

I have checked some support sites and I don't have php_gd2.dll installed in the ext directory of my PHP install directory, nor is php_gd2.dll referenced in my php.ini file. It simply references php_gd.dll (which may well be a change of refernce in PHP8, I don't know)?

I just wanted to double check that it's not related to the helperphp.php file, which is referenced in the error that's displayed.

Line 962 helperphp.php is:
$src = imagecreatefromjpeg($imageFilePath);

Line 174 helperphp.php is:
$resizeResult = WA_DFP_ResizeImage($tmpFileNamePath, $val);

and Line 78 add_banner.php is:
WA_DFP_UploadFiles("WA_UploadResult1", "NJbannerIMG", "2", "[NewFileName]_[Increment]", "true", $WA_UploadResult1_Params);