As I know from issue DBZ-920 Debezium doesn't support PostgreSQL enum type and it should be recognized as UNKNOWN. However, in my case, it's recognized as VARCHAR (see attachment) and after applying PostgresValueConverter.convertString results into a hash code of the byte array instead of its content.
All enums in my PostgreSQL database are created as:
CREATE TYPE attachment_type_enum AS ENUM ('POD', 'SIGNATURE', 'DOCUMENT');
ALTER TABLE public.documents ADD COLUMN attachment_type attachment_types_enum;