Google reCaptcha v.2 and PhP 7.3 incompatibility?

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I have reCaptcha running on 27 different sites of mine, for contact form pages running Tectite FormMail 9.15 

After I upgraded most of the sites to PhP 7.3 I started getting this strange error

To: 
From: 

The following error occurred in FormMail :
reCaptcha version 2 requires PHP version 5.2.0 or later

email: 
realname: 


Referring page was https://www.XXX.com/contact.htm
SERVER_NAME was XXX.com
REQUEST_URI was /formmail.php

User IP address was 68.7.XXX.235
User agent was Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.157 Safari/537.36

When I check, in all cases the PhP is 7.3  Not lower than 5.2.0 definitely not - it shows as 7.3

Then on that particular site getting the error, when I lower the PhP to 7.2, the contact form works again.

Given that the error is referencing reCaptcha, does this mean that reCaptcha v.2 doesn't work with PhP 7.3?   The other explanation is that Tectite FormMail doesn't work with PhP 7.3