There’s long-standing bugs for CONFCLOUD that attachments with some characters are not correctly handled by Confluence in all contexts - especially the download link leads to either a 400 or 404.
Problem is that CONFCLOUD also generates / breaks attachment names in bunches that fit that pattern.
Has any app vendor found a trick how these attachments could be downloaded despite these problems?
Reference
[CONFCLOUD-54608] Unable to download attachments that contain HTML-unsafe characters in their file name - Create and track feature requests for Atlassian products. [CONFCLOUD-58250] If an attachment has a single quote or ampersand in its name, accessing it from the Attachments menu will return a Page not Found error message - Create and track feature requests for Atlassian products.