This happens because lots of 000webhostapp sub domains are widely used for malicious activities like phishing. So, major social apps and security guards block them. We always try to minimize phishing done in 000webhost. But, as 000webhost is a free platform it is used for those activities. So, that’s why they block those domains.
If you need those to unblock the only way is buying a domain
Either you can buy one from hostinger which has a real-time support.
or use freenom.com