Definitely more than a year ago I replaced the internal 1TB Apple SSD in my MacBook Pro (Retina, Mid 2015) with a Samsung SSD 970 EVO 2TB unit (and an adapter). Quick story, no problem so far - SMART stats say 47TB data unit reads and 27TB data unit writes.
Since a couple of days I'm seeing some sporadic failure in reading a few files. SMART "Media and Data Integrity Errors" count has increased. The problem is sporadic because if I test the file that triggered the error (e.g. by computing a MD5 from command line) I see "Device error" at first, but it then becomes ok after retrying.
Is it possible to understand how serious is it?