Diesel has their own upstream losses. People are constantly using a double standard where they only include upstream losses for hydrogen while ignoring them for everything else. In reality, you are going to get closer to battery-levels of efficiency with fuel cells than with any other currently available idea. It's not even debatable given that fuel cells are far more efficient than ICEs.
Furthermore, given the needs of energy storage, in particular long duration energy storage, there are situations where you will be charging BEVs with hydrogen power. So it is not even a guaranteed that BEVs are more efficient than FCEVs, with the average case likely half-way between commonly claimed numbers. A gap that will shrink over time too, since efficiency of fuel cells can significantly improve.
The reason why I say "BEV propaganda" is because the arguments are totally ridiculous. Between the absurd fearmongering and claims of massive efficiency advantages, all while ignoring any and all limitations of li-ion batteries, it is clearly just a misinformation campaign. After all, since FCEVs are also EVs, why are there so many attacks on them from other EV enthusiasts? It is mostly a defensive strategy of misinformation and FUD. It is because more than anything else, FCEVs represent a disruptive threat to BEVs.