Currently, Illustrator apparently doesn't support all "types" of gradients present in a PDF. When trying to open the attached PDF, an error occurs and the gradient is rasterized.

However, it opens normally in other programs such as Scribus. I thought it was a limitation of the PDF producer (Inkscape), but maybe not. Please, see the discussion: https://gitlab.com/inkscape/inbox/-/issues/9185

Therefore, I ask Adobe to investigate the case and, if it is a limitation of Illustrator, to implement support for this "type" of gradient for better interoperability of the PDF parser.