New lead gets deleted right away

Your software
My Mautic version is: v2.15.1
My PHP version is: 7.1

Your problem
My problem is:
We have acivated the tracking script today on our website and when looking in the dashboard under Recent activity we see this:


A lead is created and right away deleted, what is happening here?

These errors are showing in the log: no errors

Steps I have tried to fix the problem: nothing yet