On Facebook sharing debugger:
We can’t review this website because the content doesn’t meet our Community Standards. If you think this is a mistake, please [let us know]
It seems that the entire subdomain *.infinityfreeapp.com is flagged by the FB.
Whatever name I try (existing subdomains) I get the same result as you.
Even before Facebook was sensitive to free subdomains and didn’t allow them or treat them as bad, but at least the debugger was working.
If the reason is what I stated (maybe I’m wrong)
it would be ideal if you had your own domain
or you can try with one of the other free subdomain names and see if it will go through with Facebook.