Long time that I did not play a game, and I was about to try the Slot Machine when a sliding banner came on top of the screen saying "grantgibson Has won 100 cr", vanishing after a few seconds...

Congratulations to grantgibson, by the way, and sorry that he could not win more !
BUT, I do not want to have anything I win be displayed to others!
I want to stay away from this kind of thing. My game. My life. My privacy.
No spying eyes, and especially eyes reporting to others what xyz did / won.
I find this very disturbing.

Here is the screen shot (it is on top of the words Slot Machine):
https://ibb.co/fYh8bgV

I could not find in the settings an option to deny all public announcements, and how to do it (stay private), where to find the option/command ?

(latest stable version 1.2.550 / 64 bits Windows)

It's server based : every1 is on at once and everything is monitored (both for "cheaters" and promote wins). You can't do much to bypass that. You'd have to be offline to cut yourself from the server, but then nothing would work. You'll have to deal with the winners banner or skip the event (unless I'm wrong, doubtful though)

The banner only displays wins for Triple Star and Quad Star Winners.
Single Star and Double Star wins are not displayed.

Just like in the Casino,
if you Hit a big Win, your Machine Lights up, and Flashes and Calls attention to the fact you Just won a Big Jackpot.
Then you have to sit and wait for the Security to come around and cash you out.
All the while, Everyone whom passes by, Knows you Won and who you are..

Surely we are all using anonymous/pseudo names here, not our full real names.
I'm Mr Wright and there are thousands of others, so no chance of tracking me down.
My profile picture btw is quite a good likeness though.😆
Isn't all this private enough?👍