Bugfix: increase length of request_source VARCHAR(20)

In db_create_table_log(), the length of request_source is set to VARCHAR(20). However this causes various issues later when trying to insert rows into the table because WPDB->process_fields() truncates the source to the length of the column, and then compares it to the data passed in with $data !== $converted_data. When that fails, the insert fails.

So, many inserts fail when the plugin: {plugin name} gets truncated to 20 characters.

I suggest setting it to 60, or 100, or 255 or whatever seems appropriate. This solved the problem for me.