Doesn’t sound like it failed at its purpose in that case

Fair enough, thanks for the response

I’m curious, since you’re already on Protonmail, why not use their VPN too?

There are certain sayings, phrases or slang that I may not be intimately familiar with.

This says nothing about your fluency. There are tonnes of English slang that Americans are unfamiliar with, and vice versa.
Hell, there’s a lot of Singaporean English that doesn’t exist in the minds of Brits and Americans, but Singaporeans are still fluent in English, it’s just different from what people consider “true” English.