Unable to download attachements from Gmail

Welcome @ehran. The post I’m about to link may not at first seem related, but it sounds like it will address your issue. Basically, go to brave://settings/content/pdfDocuments (type or paste that in your address bar and hit return) and turn of the built-in PDF viewer, and it has a good shot at working. If you want to use the menus instead, another user in that thread said: