Mini pill - brown bleeding/discharge

Hello everyone, I had a period at the beginning of December while on the mini pill but didn’t have one the beginning of January. When using the toilet, I wiped and noticed brown (old blood) or discharge. I’ve used the mini pill in the past but never had this happen, any ideas what this could be/mean and why it’s happened? I know you’re not doctors but I’d like to hear opinions/past experiences in others! Thanks