All of a sudden several popup messages, like this:
How can someone comments on a document if they have not read it and hence according to this message box, it is clear that Foxit Reader surreptitiously upload the user's document without consent to some cloud site to be shared. It is creepy.
This is a clear breach of privacy and I sincerely urge Foxit developers to investigate this serious matter.
May be this is caused by ConnectedPDF, something Linux users cannot turn off while the Windows version can. At least the Foxit Cloud can be eradicated by deleing the entire fxplugs directory.
In the mean time I urge all Linux users of Foxit Reader to uninstall it to protect your privacy. If you do uninstall it, make sure you delete ~/.local/share/Foxit\ Reader, ~/opt/foxitreader, and ~/.config/Foxit\ Reader.
If you need a reader with the ability to annotate your PDF document, you can use Okular which is available in Canonical or your software manager.
Apart from leaking document, Linux Foxit Reader is rather buggy - crashing randomly in different operations like annotating, printing, etc. Not only its reader is flaky, its forum is also very poorly implemented. I, a registered user, tried several times to post messages on this and so far I have yet seen any appearing. It seems to behave like a trash can.