Func_odbc only return max 15 chars on asterisk 16.20

I am using ubuntu 20.04 and installed asterisk 16.20

I set up the odbc postgresql and asterisk can connect to it and retrieve data from db.
However, if the return value is longer than 15 char, it just cut to 15 chars only.
I tried asterisk 16.2.1~dfsg (whch is the default version of asterisk on ubuntu 20) and it has no issue.

fun_odbc.conf
[testing]
dsn=postgres
readsql=SELECT 12345678901234567890

res_odbc.conf:
[postgres]
enabled => yes
dsn => PostgreSQL-asterisk
username => xxx
password => xxx
pre-connect => yes

Then the ${ODBC_TESTING()} just returns 123456789012345

Tried to find on forum and asterisk settings, can’t find anything helpful.

Is this a bug or did I miss some config?

Thanks in advance.