BUG #16435: regexp_split_to_table different behavior in 9.2 and 12.2

The following bug has been logged on the website:

Bug reference:      16435
Logged by:          prashant
Email address:      prashant_rokad@yahoo.com
PostgreSQL version: 12.2
Operating system:   Windows
Description:

Hi,

we are upgrading postgresql from 9.2 to 12.2 and observed that
"regexp_split_to_table" functions is giving different output in 12.2 than
9.2.

Sample code:
SELECT regexp_split_to_table(Column1, E',')::INT AS column1
       ,CASE WHEN column2 IS FALSE THEN NULL ELSE
regexp_split_to_table(column2, E',') END::bigint col
FROM [Table]

Also when we use function in CASE condition it is giving different output in
both version.

Sample code:
SELECT CASE WHEN column2 NOT LIKE '%test%' THEN '123' ELSE
public.fn_function_call(column2) END as a
FROM [Table]

Any help is highly appreciated.

Thanks