I remember being bullied in school and going home after being beaten by other kids
Now imagine that that beating carries on when you get home, albiet on a different form. Kids gang up on each other online at least as brutally as in the playground. Limiting access to social media removes the peer pressure to put yourself in harms way, and removes the bullies' ability to access their victim. It is absolutely not a perfect solution, as you, say bullying happened before the internet, but it does go sone way to ensuring kids have some form of sanctuary without being pressured into leaving it.
The second, and, if anything, more horrific, issue is the amount of grooming that goes on online. There is an Ofsted report Review of sexual abuse in schools and colleges that talks about this is more detail. Ideally this is the sort of problem that would be dealt with by social media companies, but unless, and until, it is, it is safer to avoid children accessing these networks unaccompanied.
this is duct tape with a side of privacy violation for everyone with barely a thought about how to even do the age verification well.
Age verification is a thorny question, and I'm certain there is no perfect answer. No smartphones for under 13s is a fairly easy first step. Children that young can't enter into a contract anyway, so the parents, or another adult have to be involved. Smartphone free childhood is a voluntary pledge, but multiple schools in the area are encouraging their parents to sign up.
Age verification for social media is trickier, but I actually quite liked the bill that was moving forward in California, which just had your device send a flag saying you were either; under 13, 13-16, 16-18, or 18+. That way, services have no excuse for serving up inappropriate content. As always, it's not perfect. In particular, there are questions about who is responsible for ensuring the flag is set correctly. I think they went astray here, and it should be the owner of the device who controls it, unless it is explicitly made for children, in which case the 18+ flag should not be available.
We are not seeing anything about funding the educational system, trying to attract more teachers, aiming for smaller class sizes, funding activities and clubs or more support for parents to spend time with their kids.
Absolutely, this is a huge problem. The VAT imposed on private school fees is supposed to be ringfenced for this sort of thing, but it's not enough. We should be putting much more into educating and safeguarding our next generation.