DeepL gives “Eu sei disso” as its primary translation but suggests “Eu sei isso” is also correct. For “we”, it gives “Nós sabemos isso” as its primary translation but suggests “Nos sabemos disso” is an option as well. Let’s see what the PP team has to say about this.
@Tomas, both versions are possible in both cases (and I’ve already checked the flash cards to make sure that both are accepted). In theory, the difference between them would be more or less like:
Eu sei isso = I know that
Eu sei disso = I know about that, I am aware of that
(we wouldn’t really see a practical difference between these two)
Here’s an example that might be more obvious:
Eu sei matemática = I know maths (i.e. I really know this subject)
Eu sei da matemática = I am aware of maths (i.e. I am aware that it exists, without necessary knowing all about it)