Influx of sellers

I’m new to this so excuse me if this is an obvious question, but one of my first products I placed an order for had 8 sellers when I bought it, and 40 sellers 2 weeks later when the product reached me. The buy box price is obviously a lot lower now there’s a lot of competition. My question is, what are some warning signs (if there are any) for this being likely to happen when picking out a product? Thanks in advance for any help with this!