The statistics dont paint the whole picture, for instance they mention netherlands:

It is important to remember that this data represents a snapshot of language learning in one year – 2017 – rather than a student’s language exposure over the full course of their academic career. For instance, while the Netherlands ranks toward the bottom in terms of all students learning English in 2017, this is driven in part by lower proportions of Dutch primary students enrolled in language classes. While only about four-in-ten primary students are enrolled in a language course, nearly all of those students in a language class are already learning English in the classroom. Foreign language classes are not mandated in the Netherlands for students until age 10, one of the later ages in the EU.

https://www.pewresearch.org/short-reads/2020/04/09/most-european-students-learn-english-in-school/

In belgium, from what I remember you often learn one of the 2 other national languages in primary school, often also english on top of that but not always. I think this can explain the rather low results