The issue is not just that a Proton employee will see that you have a premium account. It’s that the Proton employee will see and know so much more about you because they can see your whole profile.
ID at Liquor Store Analogy
Imagine you go to a liquor store, and they ask you to present your ID to prove that you’re over 18. When you present your ID, the cashier doesn’t just see that you’re over 18. They see your date of birth; hence, they know that you’re 25, not 50. They also see your gender, your full legal name, your address, your height, etc…
It’s the same with Proton. They don’t just see that Jordan Smith has a premium account. They know your name is Jordan Smith. Likewise, they know how many Proton addresses you have and what they are. They know that the last time you subscribed, it was with a credit card from Germany, but this time they noticed your cash payment came from Japan. There is a difference between a Proton’s computer system knowing that vs. a Proton employee.
1Password example
Last year, I received an email from 1Password, telling me that they were going to start charging taxes to customers from certain countries, including the one they assume I am from based on my credit card info. That means I was going to pay more for the same subscription, which I didn’t like.
I also didn’t like that 1Password assumed I was in Germany just because my credit card is German. I could be living in India for all they know. So before the tax could be applied to me, I went into 1Password’s settings and manually changed my country of residence to one where I wouldn’t be taxed.
Suppose that within a month after doing that, I contact 1Password support for a completely different issue, a bug I am noticing in their app. As the customer agent is helping me, they notice that I changed my country of residence to India when it was Germany for 10 years. They could ask me:
Hey, we noticed that you changed your country of residence to India. Do you actually live there?
I did not contact them to answer questions about my country of residence. I contacted them to report a bug I noticed in the app.
Do you see how this is invasive?
Proton example
A Proton agent could notice upon applying your cash payment that there are multiple websites for which you have 3 aliases (e.g., 3 Instagram accounts), which is not allowed and against their ToS. You did not know that (most people don’t), and the Proton agent decides to reprimand you for it with or without warning.
All you did was send cash to renew your subscription, and instead of just applying the payment, a Proton agent took it upon themselves to look at your profile and make changes to it that you did not ask for.
Can you see how your privacy was compromised?
Took a look at it and replied.