How to group concat all column names in MySQL

Question

I have a table having 122 columns, but when I try to group concat the column names, not all columns are joined together, only 35 columns are joined.

Additionally, the last column name appearing from the query of the group_concat does not get outputted correctly i.e instead of it being recurring_moratorium_principal it's appearing as recurring_moratorium_prin

select
  group_concat(column_name SEPARATOR ',') as create_qry
from
  (
    select
      table_name,
      column_name,
      data_type,
      concat(
        case
          when data_type like '%int%' then 'int_c'
          when data_type like '%text%' then 'str_c'
          when data_type like '%character varying%' then 'str_c'
          when data_type like '%uuid%' then 'str_c'
          when data_type like '%double%' then 'float_c'
          when data_type like '%boo%' then 'boo_c'
          when data_type like '%timestamp%' then 'ts_c'
          when data_type like '%numeric%' then 'num_c'
          when data_type like '%decimal%' then 'float_c'
          when data_type = 'date' then 'd_c'
          when data_type like '%ARRAY%' then 'str_c'
          when data_type like '%tsrange%' then 'int_c'
          when data_type like '%real%' then 'float_c'
          else 'str_c'
        end,
        ' as ',
        Case
          When column_name = 'group' then 'my_group'
          else column_name
        end
      ) as type
    from
      information_schema.COLUMNS
    where
      table_name = 'city')a

The result of above query i.e create_qry looks like

int_c as id, <columns name between 2-34>, int_c as recurring_moratorium_prin

What I'm I missing?