I'm curious which specific protection method turned out to be useless? Does this apply to all iPhones or a particular model? Do you need to urgently find an alternative, or is it not that critical?
Don't panic and don't just blame the built-in protection right away - usually the problem is either how it's set up or some specific circumstances. For example, if you're talking about Face ID or Touch ID, sometimes they might not work because the camera is dirty, there's moisture on the screen, or your face position is just off. If it's about virus or malware protection, iOS actually does a pretty good job catching dangerous content, but nothing can protect you from your own carelessness - like clicking on a phishing link or installing an app from some sketchy source.
Clarify which protection exactly isn't working - maybe you just need to review your settings or update your system before you start looking for alternatives.
Which protection are you talking about - biometrics or a passcode? Because "not working" could mean different things. I had a situation with someone I know: her boyfriend's Touch ID suddenly stopped recognizing his finger even though it worked fine before - turns out his finger was just wet or the screen was dirty, he re-enrolled the fingerprint and everything was fine. If we're talking about an actual breach or bypass - that's more serious, but usually it's not the protection itself that's the problem, it's wrong settings or a password that's too simple.
Give me details: what exactly happened, how did you find out, what iPhone model do you have.
The main thing is don't rush into reinstalling iOS or resetting your phone to factory settings, because the problem is often solved more easily. Try redoing your fingerprint first or setting up Face ID again through Settings → Face ID & Passcode, sometimes the data just needs to be refreshed because of a dirty sensor or changes in your appearance.
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