Why do I always have new data written below? (I need it to be written to the right)

I have data transferred to a Google spreadsheet in a row and after reaching column Z, my data is transferred below and starts with column A and continues below, but I need it to be written to the right

try: 
        result = sheets_service.spreadsheets().values().get( 
            spreadsheetId=spreadsheet_id, 
            range=f"{sheet_name}!A1:Z1000" 
        ).execute() 
        values = result.get('values', []) 

        if not values: 
            next_row = 1 
            next_col = 0 
        else: 
            last_row = len(values) - 1 
            last_col = max([len(row) for row in values]) - 1 if values else 0 

            if last_col < 25: 
                next_row = 1 
                next_col = last_col + 1 
            else: 
                next_row = last_row + 3 
                next_col = 0
        sheets_service.spreadsheets().values().update( 
            spreadsheetId=spreadsheet_id, 
            range=f"{sheet_name}!{chr(65 + next_col)}{next_row}:{chr(65 + next_col)}{next_row + len(data) - 1}", 
            valueInputOption="USER_ENTERED", 
            body=body 
        ).execute()