How to get the type of geometry column in postgres?
The geometry_columns view takes care to remove any Z/M suffixes.

You can look up the PostGIS type modifier directly in the system tables:

SELECT postgis_typmod_type(atttypmod)
FROM pg_attribute
WHERE attrelid = 'public.table_name'::regclass
  AND attname = 'col_name';


(The same can be done with postgis_typmod_srid().)