I'm not the OP of the 4.1.4 version that was posted yesterday but I downloaded it and checked it. The size difference comes from a PHP class that generates PDFs and barcodes. Namely the tecnickcom/tcpdf that you can find in github as it's opensource. All the extra code can be found inside the vendor folder of the plugin. Checking at the plugin's changelog I couldn't find any mention of a new PDF included class. VirusTotal doesn't reveal any threat