I second what @Squidlydoo says. And take a look at what Billie Eilish was saying this week about seeing hardcore porn from 11.
If you don’t use the kind of social media sites that teenagers/young people do, you really haven’t got much of a sense of what’s out there, or that the kind of porn your ten year old will see is not just Babestation style tits and ass.
I use a few social media platforms for an innocuous hobby, including Discord, Tumblr etc. Porn bot and advertising profiles regularly follow or friend you to get clicks, and if you even so much as turn to the delete page to get rid of them, you’ll still see a feed of what they have on their profile popping up and you can’t do anything about it.
This can be really extreme hardcore, the kind of stuff you absolutely do not want your ten year old to see. I’m talking violence, choking, extreme anal and so on. On one occasion as I deleted a porn link a graphic video came up of what looked like an underage child, bound, gagged, and swung by a rope tied around her neck, being graphically abused by a group of around fifteen older men. I thought I was going to be sick, and I’m a fortysomething adult. What effect does that have on a 10, 12, 13, 14 year old? (Plenty of them all over those sites, unmoderated and untraceable chat functions, hidden second profiles and servers their parents can’t see or wouldn’t think to look for.)
Yes you can report stuff and have it deleted, but you’ve still seen it. Your little kid may well be looking at stuff like that. Because it pops up instantaneously on a feed on a link someone’s sent them, and you can’t block it, and no amount of parental controls can stop it, your child’s still seen some of that in just a few moments, and you can’t ever take that away again.
Those who think it’s not a problem - go and load up pornhub and take a look around some of the bdsm or incest fantasy or gang bang categories and imagine your preteen watching even a few seconds, because you can’t stop someone showing them that stuff as soon as they get online.