I'm sure the Chinese, Russians, and other adversaries of the west will welcome any intentional weakening of network security to "protect children".

Any back doors, crippled encryption, etc, is a way in for their intelligence services. I find it baffling that politicians are so careless with their national sovereignty. It's especially worrying that a lot of populist support for this nonsense is indirectly supported by the before mentioned adversaries. There's a well documented history of especially Russian and Chinese propaganda aimed at supporting fringe populist parties. The agenda with that is complex but it isn't necessarily with friendly intentions.

Both Russia and China have isolated their own populations from the normal internet and effectively their countries run on centralized infrastructure where private VPNs are no longer allowed and traffic is monitored, filtered, and analyzed. Additionally, especially China has long targeted academic and enterprise network security for industrial espionage reasons. Weak government security has caused a few embarrassing situations across especially EU governments (e.g. Germany) with scandals related to over reliance on Chinese technology for telecommunications (huawei) and components for energy, auto motive, etc.

The point here is that those countries calling for this the most are also the most at risk of being compromised like this.