State-level bills have heretofore only required OSes to ask a user if they are of majority age. A federal bill is likely (based on the groups backing and who proposed it) to require OSes to validate (i.e. have users prove, not just assert) their ages.

Depending on what mechanisms are mandated, and who they target punishment at, it could lock 99% of users (who are not willing or capable to use means to bypass this) into tying all their actions online to a government-run database.

It’s not enough that means to bypass it exist; the government shouldn’t be able to mandate this kind of control, and shouldn’t be propagating the expectation that this behavior and level of control is normal or acceptable.