As has already been said home raid is fine but it does not protect you from loss of data through accidental deletion, ransomware, significant hardware failure of the nas, fire, flood, theft.
Really the only protection if offers is for the failure of a single HDD in the nas enclosure, and when you buy them off the shelf with HDD’s installed they are usually from the same manufacturer and batch. This is bad.
Why, well often HDD’s fail when they are worked hardest, like when you are rebuilding your data from the other HDD or HDD’s in the raid array after the failure of the first HDD.
If the disk in your array fails because the batch is bad or the firmware on the HDD’s has issues if all the HDD’s in the NAS are the same batch / firmware odd’s are you’ll see multiple drive failures.
It’s often stated that your digital data does not truly exist unless it exists three times and the nas only counts for one. Sounds like you need at least one other drive to back the nas up to.