Prior to around 1985, when a potential convert wanted to become a Catholic, it was largely a private matter.
Any person joining the Church knows that they are becoming visibly part of the Body of Christ and the communion of saints. That said, some people have reasons for wanting their journey of faith, and both their sorrows and their joys, to be private and not announced to the world. There could be any number of reasons — past sinful life, social anxiety, some invisible disability, a past trauma or tragedy in their life, family circumstances, the list goes on. Some people are discreet about their personal life due to financial circumstances — whether great wealth or great poverty. I could be fabulously wealthy or in debt up to my eyeballs, and you’d never know it. (I am neither.) It will be obvious that they have become a Catholic if they are seen at Mass, seen receiving the sacraments, or what have you.
I, for one, prefer to go to Mass more or less anonymously, and not interact with the parishioners all that much. I have my reasons. One size does not fit all. I am well aware that I am part of a very, very large group, in the long run, the only “group” that matters. Anyone who knows me is aware that I am a traditional, orthodox, faithful, imperfect Catholic. If I choose to share more than that, it’s my prerogative. If I choose not to, that, too, is my prerogative.
I know that there are some churches (not Catholic) that expect you to stand up, introduce yourself, “give your testimony”, and so on. I am thankful the Catholic Church is not that way.