Is it hypocritical to forbid your kids to do things you did as a youth? No. It is called good parenting.
But some parents have bought into the lie that it would be hypocritical to steer their kids away from drinking, pre-marital sex or fill-in-the-blank just because they did such things when they were young.
But consider what happens if you take that reasoning to its logical conclusion: Your kids could do all the bad things you did (and admit it, there were many!) without a consequence from you. There is a running joke in my house that when my daughters are 21 I’ll tell them about (most of) the bad things I did as a youth.
Hypocrisy is pretending to be something you are not in the present. Just because you did something before doesn’t make it hypocritical to speak out against it now. In fact, to do so is a sign of growth and maturity.
Now, if you get drunk then tell your kids not to drink or do drugs, that is hypocrisy. If you cheat on your taxes and tell your kids not to cheat in school, that is hypocrisy. If you are unrepentantly smoking, lusting, hating, etc. and teaching your kids otherwise, that is hypocrisy.