Where does this attendance come from?

Question

Malware

In general, the situation is this.
Launched the site, sent it to the client for a look.
He looks, everything is fine.
And today suddenly +400 visits, of which 98% are failures.
What could it be?
UPD: Direct calls, from PC. Entry points are almost all main.

Answer 1

The client himself tested your work for the quality of the code.