Invalid JSON response error message

Hi, I have recently noticed that submitting a CF7 form (with this plugin enabled) does not show the successfully sent message anymore and spinner keeps going. The email does get delivered and sync with Hubspot.

Looking at the Browser Console, the following error appears after submitting the form:

{code: ‘invalid_json’, message: ‘The response is not a valid JSON response.’}

I narrowed the issue down to this plugin (1.4.1) after debugging the website thoroughly. Currently running latest WP 6.8.3 on PHP 8.3.

I look forward to hearing from you. Regards,