Ah, yeah, I saw the account beg and took it for paywall.

The first paragraph makes it clear that the compared percentages are within countries, not between rich countries and poor countries.

The article also specifically says it’s more about in-country inequality than inequality between countries now:

When climate negotiations began in the 1990s, most of the inequality in people’s carbon emissions was between rich and poor nations. Three decades on, the situation has reversed. Now, most of the inequality in emissions between the rich and poor exists within individual countries.