They could make it so all that is known by banks is that you purchased the service. Like how Nym does it or how you can buy Mullvad credits on Amazon.

https://nym.com/zk-nyms

Ideally they accept Monero and do unlinkable payments but I doubt they will accept Monero. Hopefully they accept some crypto.

Also when they start dealing with payments there might be regulatory requirements like record keeping for a certain period.