Open Poll: CAPTCHA in text mode broken

[t-j-q]

URL: https://aplus-stage.liqd.net/tj-gmbh/projects/umfrage-4/
user: unregistered user
expected behaviour: -
behaviour: When selecting textmode for the CAPTCHA and solve it, the button to send the answer is inactive. Only when you switch to picture mode, select a picture and than change back to text mode, the send button is active. However, using it (doesn't matter whether your answer is correct or wrong) leads to an error message (see screenshot).

important screensize: any
device & browser: Desktop Safari 18.1.1 & Firefox 134.0