The thing with numerology is that the calculations themselves are 100% deterministic - your birth date will always produce the same numbers, period. The app isn't lying to you about that. But where it gets murky is in the interpretation. The answers it gives you are never really wrong because they're designed to apply to tons of people at once. It works kind of like the Barnum effect - if you read "you have a creative nature but also a practical one," it's so broad that you're gonna find it true.
The people who looked into this before me weren't wrong about the mechanics, but they're missing something: these apps know exactly what they're doing. They're not just naive calculations. They're programmed to generate text that *resonates* with you, and honestly it's not because the algorithm picked up on something magical - it's just that it asks for so little that you fill in the blanks yourself.
Personally I don't bother with it. If you like it as a hobby or to think about yourself, sure, go ahead, but don't put too much weight on it for important decisions. Numerology is basically a game of human interpretation with some algorithmic window dressing around it.