Longer answer:
Any content the moral panic at the time is panicking about will require age verification. Only things moral panickers believe is child-appropriate will be accessible without it.
This includes forums. If people can interact with each other, one of them miiiiiight be a child (no matter the forum's topic), and the other miiiiight be a pedophile. Therefore, ALL forums will be obliged by law to age-verify their users for them to be able to even read user submissions, this one here being a prime candidate.
And, note, this is a bipartisan effort in the US. All proposed bills are supported by Democrats and Republicans. Google is merely doing it on their own before the relevant laws are approved, so as to be ready when everyone starts struggling to become compliant or have their sites shutdown.