Hi
I have the same problem at many sites, did notice it started about couple weeks ago.
Now Opera version is 85 (updated just now, but all the same), and before was v84, with this problem.
As example, this page https://kilohearts.com/products/multipass , when i try to download "Multipass - PDF manual".
I disable in opera auto-open built-in pdf reader, so, by click at link it open to download pdf, and next occurs properly downloading but with hang at 100%.
Also, i tried to select "save as" and download - all the same.
But, if i copy link and past in new Opera window - it downloaded properly, without hang in end.
Also, need note that after such failed download (by normal click), and forced cancelled at end, if i try to click to link again - nothing happens, even if i close Opera and start again and open this page with pdf - clicking at link will not to do anything (download window will not opens).
Frankly, i'm use Opera about decade, and first time see such behavior.
Any solutions ?