P. S. – If you had installed a FamilyLink app on your iPhone, and couldn't find it on any of your Home Screens, you might have simply removed it from your Home Screens without removing it from your App Library. You could go to the App Library and delete it, or bring its icon back onto your Home Screen.
My guess is that you never installed this thing in the first place, unless you bought "smart home" equipment from this particular electronics manufacturer.
The app that "warned" you about the "threat" might have just been using some random icon, "lifted" from someone else's app, to make its "warnings" look more realistic. Sort of like how "phishing" mails will make use of copies of a bank's real logos and marketing graphics to try to fool potential victims into falling for the scam.