AT&T Mobile Security App

Unless you open the app and do everything through it, it's useless.

Also, from what I can see after a quick look, it doesn't do anything iOS is not already doing except provide a VPN.

A VPN that will suck up all your usage data so AT&T can sell it to advertisers.

I wouldn't touch it with a ten foot pole.

But that is just me, it's up to you.

I saw that message (scam? phish?), and thought it was rather amusing.

Paraphrasing the offer, for cybersecurity awareness day/week/month/whatever, here's a free app you can download!

Yeah; nope.

Even if it's a legitimate offer, it reeks of phishing.

And I'm already seeing a surfeit of SMS phishing or scams or simply stupid.

As for VPN support, iOS has provided end-to-end encrypted connection support since product inception, and iOS 15 and iPadOS 15 have added address-masking Tor-like facilities to those existing capabilities. And if you do want a VPN, a VPN client has been built in for many years and that VPN client will work with your own Streisand or Algo VPN servers, if you really want an added layer around the existing end-to-end encryption already provided and available.