Given that there are approximately 1.5 billion iPhone users, it's quite likely that someone else is having the same problem. Whether or not the cause of that problem is the same would be hard to say.
The first thing I would try is to delete all of your alarms, restart your phone, set up a new alarm, and test.
Other things to consider. Do you wear an Apple watch? Is your phone connected to anything else by Bluetooth (car systems are a notorious problem if the car is nearby in a garage, for example)? Have you updated to the latest version of iOS 18 (18.7.2, I believe)?
For what it's worth, I've used my iPhone as my alarm clock for more than a decade. I think it has only "failed" once or twice. And that might have been user error. For most people, the Clock app works fine. I realize that's little consolation if it's not working for you. But it does mean it should be possible to get it to work.