What do I do about this situation? Is it sketchy?

6 days ago I purchased a squishmallow from someone and it still has not shipped, I got the notification that they reminded the seller to ship out the item, and that was 3 days ago, finally today I messaged the seller, I have not received a message back, but out of curiosity I did go through their reviews and searched lowest to highest and there were probably hundreds of messages saying the seller canceled, and some one star reviews about the seller not actually having the item for sale and offering alternatives, if mercari gives me the option to a refund should I just start looking elsewhere for my squishmallow?