I used your screen shot to reproduce the database on my localhost, which I've now installed php8 on for testing.
I was able to see that the insert does fail and it is a combination of issues that cause it.
One issue was with the code and the queryobj.php file. It doesn't work correctly when using WA_SKIP and a timestamp field. I was able to correct that issue in the extension. You will have to re-install and it will create a new version of queryobj.php (version 2.28). That will correct the issue with WA_SKIP and timestamp fields.
The other issue is that you don't have form field for surname and surname doesn't have a default value specified and you have set up the insert to use the default when blank... it is blank, and there is no default, so that causes an error.
When you want to debug an insert, you can use this code after the $InsertQuery->execute(); call:
var_dump($InsertQuery);
die($InsertQuery->debugSQL());
That is what I did to debug and find the issues that needed to be fixed on your page.
