Hi Andre. I am having the same issue where the Captcha image is visible in the editing screen and the preview screen but not on the published website. I have gone through your trouble shooting steps but still have the same issue.
I am using Sitejet Builder through cPanel, PHP version. PHP 8.2 (ea-php82)
I ensured PHP version was the latest, my SSL Certificate is valid and active and I have deleted and readied the Captcha element