11g to 12c migration issue, view columns changed from char to byte semantics

Hi All,

11g to 12c   migration issue, view columns changed from char to byte semantics.

NLS and semantics(BYTE) are same for both the 11g and 12c DBs. but for few columns it shows byte semantics in the 12c database. Please let me know if anyone faced this issue.

For example:

col1 is number

create view t1( col1 ) as to_char(col1)  from table1.

In source:

Above statement in source producing    col1   - varchar2(10 char)     -  11g

Above statement in target producing      col1  = varchar2(10 byte)   - 12c

I checked all NLS_database parameters all seems same. Let me know If I am missing anything.