The user is concerned that an approver without any roles, "Tony Stark", cannot open an attachment on RITM0010000 in the Service Portal approval module (/sp?id=approval&table=sysapproval_approver&sys_id=633e03b9db00c01091a5ea42ca96192e). They wanted to know why this is.
The reason the user "Tony Stark" is not able to view the sys_attachment is that he is failing ACLs.
Here is an explanation of what is happening for Tony: attachments have a parent field. In this case, RITM0010000 is the parent record.
Tony does not have access to the parent (RITM0010000), therefore he cannot access the attachment. This is a Platform behavior/rule.
If the user wants Tony to have access, they need to configure their ACLs to allow public access (that is, to allow users like Tony with no roles to access).