iOS 13 Siri "Remind me about this" in "Chinese Taiwan" doesn't work

My device is iPhone X and iPad Pro 2017.

After upgrading to iOS 13, I set Siri's language to "Chinese (Mandarin - Taiwan)", open a mail, and say to Siri "Remind me about this" (in Chinese), Siri will only add "this" (text in Chinese) to Reminder. However, if I set Siri's language to "Chinese (Mandarin - China mainland)", Siri will add the mail to reminder successfully.

The same problem happens on iPad Pro 2017 after upgrading to iPadOS 13.

In iOS 12, Siri with Chinese (Mandarin - Taiwan) works fine.