The new comes via TheRandomizer on YouTube, who unearthed a bunch of developer cheats/codes that are functional by using a USB keyboard, presumably left in the game by accident. They also do not disable Trophies.
Houemarque confirmed however that a new Returnal update is dropping today, so the codes are likely to be removed with the update. In that case, it is recommended you turn off auto updates.
The Returnal cheat codes allow for things like spawning any weapon at your currency proficiency level and the ability to reset the stage while keeping your stuff. The full list of cheat codes can be found here.
Returnal was released on April 30, 2021 for the PS5 and you can read our full verdict on the game here.