I don’t know what study these numbers are based on, but many of them only assess certain (typically younger) age groups. In my experience, the people coming out of school today in Germany are often quite good in English.

Edit: Looked it up. The data are not based on any study but the results of test takers that aim to earn a certain language certificate. So no specific age group but still likely younger people. The sample is completely self-selected, though, so it’s hard to say anything definitive. From the Wikipedia page:

The EF EPI 2024 edition was calculated using test data from 2.1 million test takers in 2023. The test takers were self-selected. 116 countries and territories appear in this edition of the index. In order to be included, a country was required to have at least 400 test takers.

And more:

The EF English Proficiency Index has been the subject of criticism in literature. From the point of view of methodology, it suffers from self-selection bias. Instead of testing the level of English proficiency in the population, it tests the level of English of those who self-select.

This seems like a very poor basis for a country ranking.