Saw this notice when I was in a client dashboard today. They link to a Gravity PDF news article which in part states:
WordPress co-founder Matt Mullenweg has weaponized WordPress.org and appropriated the popular Advanced Custom Fields plugin from its creators. This action sets a dangerous precedent, and violates the integrity and security of the platform.
To minimize the risks to ourselves and our users, the canonical (primary) version of the free and open-source Gravity PDF plugin is now being distributed directly from GravityPDF.com. The canonical release includes an alternative update mechanism that receives new features, security updates, and bug fixes directly from our website.