Period while pregnant

So my cousin has her period (heavy) for a full month in her first trimester

People keep saying that people getting spotting or intermittent bleeding is what people get not their period but that’s it light but a lot of the women in my family have experienced this

Obviously it’s not really a period if they’re pregnant but why would it be so heavy and so consistent?

And no one in my family has two uteruses just PCOS and tilted uteruses

Has anyone else experienced this?