PHP 7.4 update not working with the PRO version

I updated our company's PHP version through our host and when I went back to check the website I received a fatal error message. Reverted back to the regular (free) version and the site was back online. Activated the PRO version again and received the fatal error message again. deactivated all the plugins after and then only got a white screen. I'm currently on the free theme. Is the PRO not compatible with PHP 7.4?