If you're okay with it, just be normal and respectful. You can carry on with your activities as usual. If it makes you uncomfortable, have an honest conversation with her about your feelings.
Some people in society would be shocked and offended. They might see it as a violation of social norms and decency. Conservative groups would likely condemn it and use it as an example of the breakdown of moral values.
You should firmly and politely tell her that it's not acceptable. Explain the importance of respecting social norms and the feelings of others.
You could start by giving her a warm welcome. Maybe offer her a cup of tea or coffee. Then, have an open conversation. If she seems tired or stressed, give her some space to relax first. But if you are worried, gently ask her why she is late. Try to approach the situation with kindness and patience, rather than being accusatory.
In the privacy of one's own home, different couples may have different views. Some may consider it a normal part of being comfortable at home, as long as it is within the boundaries of what both partners are comfortable with. However, if there are guests or children around, it might be a different matter.
React calmly and rationally. Sit down with her and discuss the pros and cons. You can mention things like the potential stares she might get, even if it's allowed. Also, talk about how it might affect your vacation experience together. You could say 'I understand your desire for freedom on vacation, but we also need to think about how others will perceive it and if it will make our time there more enjoyable or more difficult.'
Don't overreact immediately. Just take a deep breath and try to understand her perspective first.
Well, if it's just the two of you at home, it could be a matter of personal choice and comfort. Some couples are very open and relaxed in their own space. But if there are children in the house, it's important to think about what kind of example it sets. Overall, as long as it's consensual and doesn't violate any moral boundaries within your relationship, it might be okay in the privacy of your home.
Perhaps she was a bit shy at first, but then gradually became more comfortable as she saw other women around her. She could have felt a sense of liberation and enjoyment as she embraced the unique atmosphere of the topless beach.
She could get kicked out of the bar. And she may face public shaming or negative comments from other people in the bar.
You could simply smile and ask her to share the story with you. It's a great way to show your interest in her life and what she was doing.