First articles on medium are usually free.

This probably happens because these links aren't paywalled for everyone. I, for instance, have never encountered any paywall on any medium.com article; whether that is because I have my browser configured to discard all cookies whenever the browser is closed (and I close my browser very often), or because I have it configured to disable Javascript by default unless the site is whitelisted (and medium.com is not on the whitelist), or something else, I don't know.

It's both, actually.

The Medium popup only comes after visiting a few articles, and it is shown with JS.

Since I do most of my reading on my phone, I find this iOS shortcut someone posted on HN a few months back of great use for bypassing almost every paywall I have come across.

I extended it to also work on Medium by using Twitter as the referrer.

Shortcut: https://www.icloud.com/shortcuts/95928cdef80a46d892d05a58a88...

The FAQ already says paywalled links are allowed as long as there's a workaround.

It does, but that was a bad decision that has made HN worse; it's time to revisit it.