Abstract: Reliability is a central aspect of hafnium oxide-based ferroelectric field effect transistors (FeFETs), which are promising candidates for embedded non-volatile memories. Besides the device performance, understanding the evolution of the ferroelectric behaviour of hafnium oxide over its lifetime in FeFETs is of major importance for further improvements. Here, we present the impact of the interface layer in FeFETs on the cycling behaviour and retention of ferroelectric silicon-doped hafnium oxide. Thicker interfaces are demonstrated to reduce the presence of antiferroelectric-like wake-up effects and to improve endurance. However, they show a strong destabilisation of one polarisation state in terms of retention. In addition, measurements of the Preisach density revealed additional insight in the wake-up effect of these metal-ferroelectric-insulator-semiconductor (MFIS) capacitors. Graphic abstract: [Figure not available: see fulltext.]