Whether a prologue is "good" or "bad" tends to hinder on reader preferences. However, where author's craft is concerned, a good prologue should achieve the goal the author set out for it. What I mean by this is that prologues have a number of functions and the success of a prologue is dependent upon how it supports the story and engages the reader and whether it achieves the intended purpose.
The beauty of a prologue is that it gives the reader a choice of whether or not they want the information provided in the section. The story is the story but the prologue serves to establish some form of context. In non-fiction texts the prologue might provide important historical context or information about the author's life that influenced the story to come. In fiction writing a prologue might be used establish an understanding of the fictional world the reader is about to enter (this tends to be the kind people refer to as an info dump), establish mood or foreshadow upcoming events.
These are not the only ways to effectively use a prologue in your writing but as an author it's critical to remember that prologues are an important context tool you have at your disposal. When they're used correctly, they can provide a deeper layer of understanding to the reader. Prologues establish a partnership between the author and the reader as well because the reader knows they can skip that part. When the reader chooses to consume the prologue it's almost like an agreement that the reader is willing to engage in the upcoming text fully.
Tip: Writing a prologue can feel daunting when the rest of the writing isn't fully established. Save the prologue until the end when you're finished with your piece. Once you feel good about the text itself, re-read it and ask yourself if there are any questions you'd have if you were reading it for the first time. Is there anything missing that doesn't fit directly into the text? Are there events that provide meaning to sections in the story? Then design the prologue to address the needs you found in the completed piece.