iirc the Foundry and AoN devs both get the info from their own pre-release copies of the rulebooks - because they're all volunteers their schedules don't necessarily align, so content will often turn up on one before the other. The PF2e system for Foundry is mostly so good because Paizo encourage those kinds of projects instead of quashing them over IP rights. Cultivating a community that actually likes them is like half of Paizo's business plan.