Multiple purchases “pending” for several days then cancelling. What’s going on?

I’m seeing a trend of a SKU selling through all of it’s inventory and then the orders just sit as “pending” for several days before ultimately cancelling. I’m not sure if it’s a competitor, a bot, or if it’s legit.

Also it should be noted that my products are PL and I’m the only seller. However, my niche has a lot of competing brands.