You know what, I'm gonna say something extreme (sic).
Parents should adapt to the current era and stop waiting on others to deal with their kids. It's 2024, most of the parents with school age children, are what? 20-50 years old? That means they have at least 1-2 decades worth of pc/phone using experience, they should be able to learn how to block sites/games/whatever on their kids devices or even in their home network. Granted that's not a waterproof solution but think about it, either the kids give up and start focusing on their studies or in order to circumvent their parents they start studying stuff that could prove just as useful in their future.
(/rant)
Blocking sites, games, whatever are all solutions which aren't really solutions. For one, kids are usually far more tech adept than their parents. Certainly I know as a kid I and every other kid I knew effortlessly bypassed all school network restrictions on what you could access with just our 10 year old brains. And things like dealing with chronic tech addictions where the tech consumption is actively consuming their life and stopping them from carrying on with their life and their development, yeah you can just take away their ability to access tech through logistical means, but for very practical reasons you can't isolate your kid from tech forever without also isolating them from contemporary society itself. And you don't address the underlying issues of safety or self-discipline, so you end up going to war with your own kid and the moment they're free from your oversight will go back to the same patterns of self-destructive behavour.
The only real solution is to parent your kid, teach them how to use the internet safely, how to have fun without falling for a skinner box addiction, the same way you might prepare your kid for dealing with drinks, sex and gambling without completely losing themselves in the sauce. But this is where the deeper problem comes in; society is fucking broken right now, and there is no support at all for parents to actually raise kids. So median income in the UK for a household is £23,000 but the median cost of just living in London is £33,000 whilst the average cost of raising a single child is £12,360 per year. So it's utterly nuts when young people are already starting their careers in debt, seeing most of their labour wages lost to rents, sustenance and transport, and are then somehow also supposed to not work overtime and raise their kids. Some parents are just fuck ups sure, but a lot do not even have the tools to not fuck up, because every day is bleeding into the next