You can't back up PS5 game saves to a USB device
Players can only back up their PS5 game saves via the paid-for PlayStation Plus service, with USB transfers no longer an option.
Players that want to back up their game saves for PlayStation 5 titles will need an active subscription to Sony's premium PS Plus service in order to ensure their saved data is copied to the cloud.
Back on the PlayStation 4, you could either back up saves by copying data to a USB storage device or uploading to the cloud, meaning players that don't pay for the subscription service had an alternative to using PS Plus. On the PlayStation 5, however, Sony appears to have removed the option to back up your data to another physical device (thanks, TweakTown).
Players that want to ensure their game save files are backed up on Sony's next-gen console are effectively finding themselves locked out by a paywall.
The small silver lining is that players that want to transfer saves from their PlayStation 4 to a PlayStation 5 can copy over saves from their previous-gen machine onto a USB and load that onto a PS5... you just can't do it the other way around.
Say, for example, you wanted to carry on your Assassin's Creed Valhalla game on PS5 after starting on PS4. You'd be able to copy your saved data to USB from PS4 as usual. But you would not be able to back that data up once you were playing on PS5, unless you have a PS Plus subscription.
This may pose problems for players that want to protect their saves who may not be able to afford PS Plus subscriptions, or who may live in areas that don't have a consistent internet connection.
At the time of writing, Sony has offered no statement about why this feature has been removed between generations.
At least the hardware is winning people over, though: in our review for the PS5, we said that it really felt like a next-generation experience and across the industry the reception to Sony’s new console has been pretty warm.