As the problem is adults trying to groom kids, the answer is robust detection and enforcement of the current anti-grooming laws.

It's ironic that people supposedly care about this when there's also a child rapist/murderer being kept safe as President without being held accountable for his crimes.

I suppose this law could be used as a defense against getting caught grooming minors - "I thought they were adult as surely a kid wouldn't be able to access that chat group"