A solution to this is to use a type hint for row as follows:

with open(infile, encoding='utf-8') as csvfile:
    reader = csv.DictReader(csvfile)  # Read CSV as a dictionary
    for row in reader:
        print(row)
        row: dict[str, str]  # type hint which specifies that row is a dict with string keys and values
        symbol = row['SYMBOL']
        print(symbol)