PHP 8.0 Causes Spinning Wheel Issue

First of all, I want to thank Takayuki Miyoshi for all his effort creating and supporting this great plugin!

We have been using the 3rd Party Integration Plugin with CF7 for quite a while and the website uses the most recent versions of WordPress, plugins and CF7 with reCaptcha v3. The server is at PHP 7.4.

When server is set to PHP 8.0, and we try to submit a form, the status wheel just spins endlessly.

The form email does send and the form is received by the API endpoint URL, but on the frontend, the status wheel just spins.

The debug report says:

**FORM**
Title: Contact Form Test
Intended Recipient: MY EMAIL ADDRESS
Source: https://boeing737max8litigation.com/wp-json/contact-form-7/v1/contact-forms/983/feedback

**SUBMISSION**
Array
(
    [timeout] => 10
    [body] => {"firstName":"Test","lastName":"Tester","phone":"555-555-5555","email":"[email protected]","street":"555 Main","city":"Anytown","state":"IL","incidentDate":"05\/31\/2022","birthDate":"06\/13\/1991","description":"Test","sourceType":"Internet","websource":"CLO Website (direct intake from our website)"}
    [headers] => Array
        (
            [Content-Type] => application/json
        )
)

**RAW RESPONSE**
Array
(
    [reason] => Could not locate success clause within response
    [safe_message] => Success Clause not found
    [clause] => Success!
    [response] => {"message":"Success","logId":null,"isSuccess":true,"intakeId":"a0C3i00000H6zsqEAB","accountId":"0013i00002zQrpUAAS"}
)

Any help would be appreciated.

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