Issue with an old iPhone

Spam. Nothing to worry about. Do not touch any buttons/links. Ignore/delete it and move on. Stay off the website where you were when that popup appeared. Nothing can check your iPhone for viruses, let alone report that to you.

You are looking at a scam message that this trying to trick you into buying completely useless software to fix a problem that does not exist.

Delete the message and keep working.

By the way, the website that you were visiting when the scam message appears was paid to display the scam. That tells you something about the quality of the site.

Don’t press that button as it is a scam. See Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

You are downloading stuff from a site that is sending you stuff you did not order. I would avoid that site.

That message is fake.

You already mentioned this in your other post.