Technology

Almost all the solutions I read in this thread go from one extreme to the other. Here are my PERSONAL perceptions:
Taking away children's smartphones or limiting them is obviously not the solution, and if we did, in the process we would be violating multiple rights, to privacy, freedom, access to information, etc. There is no guarantee that they can be fulfilled in other ways.

But children are not responsible enough to use ICT (Information and Communication Technologies) without adult supervision!

That is simply false, the responsibility and use they make of ICT is not something that is born by magic, it depends completely on the education they receive, if you say that your children are not responsible enough to use a phone as their parent you are the main responsible. From that, start thinking about how to educate them to be more responsible, not all parents are as good as you at making sure you don't blind them.

Regarding privacy, there is a great discussion about parents and the privacy of children and adolescents, however, I will ask you some important questions.
Did you tell your parents everything? Didn't you divide school life, friends, and family? What would have happened if you had had ultra-religious or extremist parents in some way who limited your way of acting and your access to information that they did not consider part of their values? These three things have been happening for a long time.
I also read in a comment that people don't verify information. Many organizations, governmental, family, religious, etc. They don't want people to verify what they're told, but that doesn't mean we can't make our voice count to make it happen.
Another thing I read is a problem mainly in the United States (I'm not from there) and it's the iPhone, it's not worth wasting your time here, I mean bullying still strongly exists there. They need a big change in their education as the first important step in the discussion, I wish them luck.
Everything has to do with everything, and the general economic situation in the world keeps parents working instead of taking care of their children, but at the same time if we leave them the cell phone we will get worse. Taking measures on our side is not going to help, we have to generate consensus on the use of ICT.

Sorry for my English, I am learning the language and writing this text with the support of a translator, some things could not be expressed as I wanted.
EDIT: With translator, I mean google and LanguageTool.