For this:

These two statements are in conflict and cannot both be true.

“There is no section mentioning penalties for individuals entering false age information. You are completely free to submit whatever age you wish.”
“It’s literally just closing the giant loophole of “I’m totally over 21” that we all made fun of for years.”

They are not in conflict, because the onus is on the parents to set up a child's account. So if the parent did their job, then the child can never click "I am over 21" because at the OS level it's blocked. They would need their parent to bypass that again. For adults, on your device, you simply never set up a child's account, and you don't need to worry about it. So yes, I consider that closed. A child loses the ability to click "I'm over 21". Adults if anything hopefully don't have to click that anymore, but I'm guessing for safety they'll still force us to tick the box.

And what if a website or app doesn’t check this or add a nudity flag for the device/browser to check? Do you think porn sites in other countries will care?

So far this isn't for the web at all, but I see this as clearing up the grey areas. Maybe they don't care, maybe they do. Maybe it puts more power on the browser to help stop it. If a website or app does not listen to it there are consequences for it, but seeing how it's quite literally a boolean check it sounds pretty easy to be in compliance. That's the monetary damages we saw above.

I don't know man, I see this, which is a simple thing a parent can set on an account: are they a child or not. Or, the alternative, which is everyone has to upload their government ID to some third party site, have it stored for all of eternity, and collated and collected, just so they can access discord, or social media, or whatever. The thing is that I do not believe there exists governments right now who are willing to let any of it slide anymore, they are demanding that something be done. Nothing is no longer an option. If we have to choose one of the options, (and by not choosing it means they will choose for you), this seems like the safest most privacy focused option.