This is true of ALL parrots. Babies are a walk in the park in comparison. When they approach sexual maturity (which varies by species) hormones rev up and stay up for generally a few years. After that, you have an adult bird (with adult sex hormones). Think about a baby, vs a 13-14 year old, vs a 21 year old...You never get your baby back to that place BEFORE hormones. Just like a 13-14 year old feels things intensely, so do parrots. A sassy 21 year old is still a lot less nice than a baby...but maybe a bit more level than the 13 year old.
A lot of people make the mistake of treating baby parrots like lap dogs and establish all of this inappropriate and preferred behavior (from the bird's perspective) that will lead to a hormonal, dependent ,"crazy" bird in adulthood....but once you establish "favorite things" you can't just take them away from them when they hit puberty without upsetting the bird (even when you realize that you have to), which is why you need to start young in terms of the behaviors you would expect post puberty (even if they won't be sexually mature for many years). NOTE: EVEN a bird that lives with an expert trainer is far more difficult / a much more intense commitment than most other pets in terms of the detail and knowledge they require...coupled with their long life-expectancies (which sound great, until it doesn't--for many, this is the case). You should never pet anywhere other than the head or neck...never allow access to shadowy spaces...teach them to play with toys...learn how to handle the behavior (ABA is a great start)...12 hours of sleep...balanced diet..at LEAST 1x yearly visits to an avian certified vet if at all possible (exotics vets are not the same). It can be tempting to carry your baby all around and take it with you everywhere, but what does that look like in 4 years when it sees you as its mate and gets jealous, or when you have to go to work and have a bird that doesn't know what it means to feel okay for periods of time alone? YOU MUST take them out at least 3-4 hours a day, but you also have to literally teach them to play etc...teach them in small doses (this doesn't mean locking them up and leaving).
Bottom line though, you will be bitten (we all have been)...but if you are, it's almost always because you aren't paying enough attention to the signals or because you don't know enough about behavior theory etc...so a "nippy" bird is a bird whose owner doesn't understand when to back off (despite clear "don't touch me" vibes) , or a bird whose owner hormonally stimulates it...or a sick bird..or a bird who has had its bad behavior inadvertently reinforced .
It is like adopting a VERY complicated, smart, child with unique needs and a totally different outlook on the world. I feel like this question worries me a bit because it is SUPER general...
Dogs and cats are much more intuitive and much easier than parrots in general (dogs and cats--yes, even cats-- move fast and bond quickly...they are forgiving in comparison and they brush things off easily- they also are domesticated, whereas parrots are literally still wild animals- even if hatched in captivity)...A parrot is a VERY complicated pet in comparison. From the changes they require in terms of the types of cleaners you use (including the fact that you can never use scented products like air fresheners, plug-ins, candles, oil warmers etc...fabreeze...it's all out..Teflon/PTFE/PFOA/PFCs= also out..perfumes etc...burning food, smoke, vaping...all very bad (and in terms of teflon, it can kill them even if you use it an entire floor away with doors shut). They also are VERY sensitive to changes...be it new furniture, a new boyfriend, a work schedule shift, hairstyle change etc etc etc..then there are dietary issues and the fact that they will hide illness until they are in an emergency situation...