Malware had infected 15 per cent of my iPhone?

It is a scam message. Close the offending page, and avoid sites that are involved in such bogus advertising tactics.

It's an ad served to you by a website.

It's designed to scare you into buying useless software.

Install an ad blocker.

A malicious message.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Spitrunner wrote:

What is this