The specific reason for each Df'ing had been announced in the '60s, and then the reason was changed to only 'Conduct Unbecoming a Christian'. When that change happened, resulted in much speculation in the remaining congregation that the change was necessary because of law suits.
I recall when the announcement was again changed to 'first name, last name is no longer a Jehovah's Witness' that was again met with speculation with regard to the reason why the change was necessary.
As the Public Talk and WT study was considered a public meeting, Df'ing and other private congregation announcements were normally reserved for the weeknight Service Meeting, but I can recall one occasion where a Df'ing was announced on a Sunday, which the congregation found more shocking than the Df'ing itself.