Migrated data with Special Characters Counted as 2 Characters in DB2 Linux
Every character needs 1 byte in a single-byte database, but it may need from 1 to 4 bytes in a UTF-8 database.
When you specify VARCHAR(N) for a column, N is defined in string units.
OCTETS means bytes, and CODEUNITS32 means characters.
In your case N probably is OCTETS, and since Ñ character requires 2 bytes (OCTETS), then whole string length in the UTF-8 database is 7.
Character strings