What happens when ZFS RAID0 or RAID1 (single disk) detects data faults?

There are many articles about how ZFS protects the data and detects bit rots etc. There is even a question asking about ZFS on a single drive. zfs on a single device: what happens when a file is corrupted?
But the answer is use copies=2. What I am wondering is what exactly happens if one have no redundancy.

However I could not really find what happens exactly if there is no redundant copy of that data. People who spread FUD seem to imply that a single bit fault will cause all data to be lost. However it seems unlikely that ZFS is so badly designed.

So what really happens from the point of OS when ZFS finds a bit rot and there are no redundant copies of data? Does the OS show IO Error when accessing that specific part of filesystem/file?

Perhaps rest of the things continue working? If the part with error is overwritten then error disappears? or ?

Is there any clear documentation about these failure modes that you can point to?

Thanks!