Thingiverse is relying on some internal feature of a Google API to generate QR codes inside Thing attribution HTML files that are included in the ZIP download. If Google decides to change this API or block external access, these QR codes will break, even for previously downloaded files.
Possible solutions: either use a standalone javascript QR code generator embedded in the downloaded file, or generate the QR code image on the server and embed it as an image in the ZIP file.
Thingiverse is relying on some internal feature of a Google API to generate QR codes inside Thing attribution HTML files that are included in the ZIP download. If Google decides to change this API or block external access, these QR codes will break, even for previously downloaded files.
Possible solutions: either use a standalone javascript QR code generator embedded in the downloaded file, or generate the QR code image on the server and embed it as an image in the ZIP file.