What we see is not what we understand, what we produce is what we know. In this talk, I will present what we know (or don't know) about galaxy clusters by reproducing them with different state-of-the-art hydrodynamic simulations from the300 collaboration project (https://the300-project.org/). In detail, I will focus on 4 different aspects: the cluster dynamical state, the lensing crisis, the predictions with ML and the filamentary structures around the cluster.
