Which content-blocking APIs are you talking about? Blockada just started hosting a DNS server. Google just made it so that blocking decisions can't be made locally anymore and all my used domain names are sent to a third-party server. Given deployment of SSL and even cert pinning in almost all apps I know of, I doubt the local VPN API allowed them to gather much more info than hostnames either.

EDIT: I see you're affiliated with Google Play. You should've lead with that.