another issue is if a column is defined as varchar(50) as example

once a data is loaded, the full_data_type is changed to string. I tested multiple times, and looks like that's also an issue

before

after data loaded with a insert statement

full_data_type is changed

select column_name, full_data_type, data_type, character_maximum_length, ordinal_position, *

from system.information_schema.columns