data table size is too large when load data from RDS into Redshift using Glue

Question

I am new to data engineer and I try to load 3 data tables from RDS into Redshift using AWS Glue.

3 tables in RDS only have maximum size over 100Mb. But when I load data using Glue (or copy command in Redshift through S3) , the tables data size go up to Gb.

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Does anyone know this situation and help me to solve this problems?

*Note: 3 tables have 20+ rows, and I use Redshift Serverless for data warehousing.

1. The target table with 65Mb and 500K rows has about 28 columns.
2. The target table with 3.2Gb and 46K rows has about 22 columns.
3. The target table with 2.5Gb and 80K rows has about 51 columns.