You can argue that he was talking about this season when trying the 4-3-3, his previous comments about formations were in regards to how we played last season.
Perhaps you’re right, but then again he mentions Coutinho, who of course has not been here this season. Either way, to say we’ve never played a 4-3-3 is not something Klopp seems to agree with.
And I haven’t even argued that it is a 4-3-3, but it’s the simplest way to describe the formation when we use 3 central midfielders behind Salah (still the striker, but off the right), Firmino (slightly more advanced than he’s been for most of this season, and no one directly ahead of him) and Mane on the left hand side. When Coutinho was here, a few times he was one of the midfielders, with Mane to his left, and then we also played the formation that is more similar to what we’ve used this year. When Mane was on the right, we had 2 central midfielders and Coutinho off the left with Firmino (droping deep) and Salah central.
It might be technically wrong to call the first 4-3-3 and the other 4-2-3-1 (or 4-4-1-1) but when talking about us, and when comparing the two and how we can play, I think that works. It is just a shorthand for the two, so you don’t have to write a tactical breakdown of his role every time you want to talk about our team.
For instance, we could play our 4-2-3-1 tonight, although our most recent one, with Keita in the ’halfspace’ on the left, Mane on the right and Firmino behind Salah central. But perhaps it will be the 4-3-3, with Henderson, Fabinho and Wijnaldum behind Salah, Firmino and Mane. Everyone would get the difference between the two without me having to mention every detail, right?