[SOLVED] Attachment can't be downloaded on mobile

I can reproduce this, but only on mobiles. On my desktop the downloads are ok with different browsers.
EDIT: mit Chrome auf Samsung kein Problem

see a print screen from my Samsung, when I try to download a pdf from attachments in JEM.
The same in the desktop works well!

I tested now on Joomla! 1.9.4 and JEM RESPONSIVE2.3dev2.0:
I can upload pdf-attachment from backend and from frontend, on the desktop I can download and read this pdf (tested with firefox), but from my Samsung Galaxy 6+ (2018) I can't open this pdf-attachment (with the posted answer).

I tested again, uploading a pdf-attachment from mobile phone. Upload worked well.
The download from mobile didn't work, the download from desktop worked well!

for me it seems so, it has to do with newer things I don't know in Joomla or somewhere! Before I never encountered that.

I continued testing on my Samsung mobile: with samsung internet and chrome the download works.
I tested more: in my case the problematic part seems to be google drive pdf viewer!

I tested on my samsung with firefox, edge, chrome, samsung internet: I always can download pdf and other files!

EDIT: Problem seems to be google drive pdf viewer on samsung phone!