Many, many years ago I was asked to implement a filter like that for usernames. I said right away that it wasn't going to work well, but I did implement it.
Next internal build, the CEO can't create an account. With his real name.
It worked exactly to spec; I added a debug print and showed everyone the "bad word" it tripped on. The idea was promptly rethought.
I feel like the AI did you a favour here.
Now I'm trying to figure out which word that would be, but yeah.
That reminds me of a bug I fixed where my bosses boss found it, we did everything, my boss at the time forced us to deploy anything and call it fixed. Then someone else saw it half a year later, I finally figured out the root cause and fixed it (localStorage vs sessionStorage) and my boss was acting like he didn't know what I was talking about, but I could hear it in his voice. I didn't press too hard, I just pushed the real fix out. It was basically a "client-side" bug of a gift card balance saved in localStorage that never updated, so I changed it to sessionStorage. Not quite the CEO, but the guy below the CIO finding a bug can worry just about anyone.
In my case, the regex would have been for a friend to filter reddit or discord slurs, so not as awful.
> Now I'm trying to figure out which word that would be
I once had Shi Tao as part of an email username. It tripped filters periodically.
Ah the classic Scunthorpe problem