With Photoshop, do you see "Lorem Ipsum..."? If so, open Preferences > Type. See if "Fill new type layers with placeholder text" is checked. Uncheck it if it is checked.
Unfortunately, it's not placeholder text. Whatever I type, the text will auto repeat in the text box. The screenshot below, the revers type are the text I type, rest of charactors are auto type/fill by Photoshop.
Oh, I see. If you are using Zhuyin Traditional Chinese IME (input method/input source/keyboard), we are aware of the issue with the IME and working on the fix. In the meantime, you can use other IME such as Pinyin Traditional or others available on Mac. Or, delete all the extra characters appear to the right of insertion cursor. I understand your pain caused by this issue. Thank you for your patience.
If this is not Zhuyin Traditional Chinese IME, please let me know what IME you use.