I'm gonna be honest here, I think a lot of people have went from underestimating the difficulty of Returnal due to the usual cakewalks that Playstation first party titles tend to be, to overestimating it massively.
We all know game journos are not the ones to listen to regarding difficulty in games, and there is such a wide range of opinions on it. I have seen some journalists say they have played through 4 of the biomes within 6 hours with little challenge whilst seeing others say they had spent 11 hours and still not finished the 2nd biome yet.
I believe this game will likely be near enough to Doom Eternal in regards to difficulty, being easy to pick up yet hard to master, with a massive emphasis on staying on the move with combat encounters acting as puzzles you have to find a solution to instead of just blast these enemies, job done. Skill Up's preview explained as such, with him describing combat encounters as puzzle like situations.
It will definitely be a challenge, but I am thinking it won't be the Souls in Space game some journos are making it out to be.