That's how random samples work. A small number like that is enough to get a decent estimate of the entire population. Give ar take a percentage point if three. That is, if the sample is actually random. That's actually near impossible to guarantee, as people who pick up their phones (or answer their door, or walk in the street and allow folks to ask them a question, or answer a letter) are different from those who don't.

The content is still visible though (at least on my end)

it emerged AfD party members had attended meetings with neo-Nazis and other extremists to discuss the mass deportation of migrants, asylum seekers and German citizens of foreign origin deemed to have failed to integrate.

Not just illegal immigrants, also everyone they don't like. And in cahoots with self declared nazis.