I’ve had 2 about 24 hours apart. It looks like stripe is doing its job by detecting them as failed, although I wish there was more information on origin / credit card used etc. From working on big (£k m) sites in a past life these things happen quite regularly. I suspect someone has found a way to place lots of woocommerce orders with a bot – especially as I saw no analytics activity for either.
As long as the payment doesn’t go through I wouldn’t worry too much. If it does then cancel and refund otherwise it will go to chargeback when fraud is detected. This can, in extreme cases, get your site blacklisted by the payment provider.
