Uncaught Error: Cannot use object of type stdClass while showing the list using WP_List_Table

    $this->items = $this->get_table_data();

If this line is triggering the error, then the reason is probably that items should be an array of arrays, not an array of stdClass objects. But you don’t need to change much, as get_results() does support returning arrays instead of objects (which is the default).

Instead of

$get_bl_list = $wpdb->get_results("SELECT * from {$table} where bl_is_active=1",);

do

$get_bl_list = $wpdb->get_results("SELECT * from {$table} where bl_is_active=1", ARRAY_A);