UITextField textColor changed after clearing the text

Question

The text color starts out as red and changes to blue after clearing the text.

@interface ViewController ()

@property (nonatomic, strong) UITextField *textField;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 100, 30)];
    self.textField.textColor = UIColor.blueColor;
    self.textField.text = @"hello world";
    NSAttributedString *attributedText = self.textField.attributedText;
    NSMutableAttributedString *mAttributedText = attributedText.mutableCopy;
    [attributedText enumerateAttribute:NSForegroundColorAttributeName inRange:NSMakeRange(0, attributedText.length) options:NSAttributedStringEnumerationLongestEffectiveRangeNotRequired usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop) {
        [mAttributedText addAttribute:NSForegroundColorAttributeName value:UIColor.redColor range:range];
    }];
    self.textField.attributedText = mAttributedText;
    
    [self.view addSubview:self.textField];
}

@end

The expectation is that the text should always remain red. Why does UITextField textColor changed after clearing the text?