Most tracking checkers load your homepage and list the tags they see. That proves the code is installed. It says nothing about whether a lead is reported, because the conversion only fires when someone sends the form or taps the number, and a homepage load does neither.
On our own site, a homepage load sends Google Ads four requests, all carrying our account id, and none of them is a conversion. They are page views and remarketing pings. The conversion goes out only after the contact form is sent, with its own label, a hashed copy of the email, and an order id so Google counts it once. A checker that sees the account id and calls it a conversion would pass a site that never reports a single lead.
So the check does what a customer does, then reads what each platform would have received. The form is answered by us, so you get no test lead, and the reports are cancelled, so your ad accounts never count a fake conversion.