I think they are using PPP-adjusted values? If you click through to their definition (https://ourworldindata.org/higher-poverty-global-line https://ourworldind

I think they are using PPP-adjusted values? If you click through to their definition (https://ourworldindata.org/higher-poverty-global-line https://ourworldindata.org/higher-poverty-global-line) they say that incomes are expressed in "international dollars" and "One international dollar has the same purchasing power as one US dollar in the US".