And in france it was many times in the news about a group of friends who were arrested for using Signal.

Citation needed. Your third- or fourth-hand account is so vague that I wonder if the devil has been lost along with the details.

It piqued my curiosity. The only references I could find were the Telegram CEO being arrested earlier this year (widely reported on) and a group arrested in 2023 for associating with a Kurdish militant faction (YPG). That incident had some misdirected media attention towards the encryption tools used.

I have heard they (South Korea) plan on building skyscrapers with screens covering the buildings, so that they can project the background skyline via the screens. The effect would be to render the building almost invisible. Seems like a lofty goal, so I am not sure if they are still pursuing that project or not.