We have a problem with the attachments on ArcGIS Server. When we request an attachment, it's downloaded rather than opened in a new browser tab.
This behavior is explained by the http header in the server's response which is the following:
Content-Disposition: attachment; filename="Photo 1.jpg"; filename*=UTF-8''Photo%C2%A01.jpg
On all other ArcGIS Servers (also 10.8.1) where we did the test, the http header is:
Content-Disposition: inline; filename="Photo 1.jpg"
In that case, the file is opened in a new tab.
We can't figure out why ArcGIS Server adds one http header instead of the other.