SELECT query fails after pg_upgrade as the conditional operator fails

We are seeing this intermittent problem after we upgrade from postgres 9.3.12 to 9.6.12
We failed to query few of the rows in the table using a TEXT field.

The following query fails:
SELECT * from table where jobid = 'foo';

Whereas the following is passing:
SELECT * from table where jobid LIKE '%foo';
SELECT * from table where trim(jobid) = 'foo';

We were suspecting some leading invisible characters before 'foo'. but the following queries went well:
SELECT left(jobid, 1) from table where jobid LIKE '%foo';
SELECT ascii(jobid) from table where jobid LIKE '%foo';

We have tried upgrading to other versions like 9.5.16 and 9.4.21 but faced with same issue.
Old datastore from 9.3.12 has saved so we are able to reproduce it consistently.
Observing issues with same rows every time (not random)
Ecoding: SQL_ASCII
Platform: RHEL 7.5

Any help would be appreciated.

Best Regards,
Nithin.