I am surprised that Google spends so much time tackling custom ROMs via it's Play Integrity API. If only they paid that much attention to say, curating the Play Store more, it had be much better for everyone
Stock android experience is the exception, not the norm, sadly. Some manufactures like Motorola or HMD have a light touch and close to stock but other ones don't. The worst offenders are Chinese brands who twist it so much and without much benefit(Atleast, Samsung's ONE UI is customizable as heck, can't say the same for Realme's).