hello @Dogalicious thanks for your post. I don't think it's a global Apple issue, but there have been reports (and I've experienced it myself) of older Safari browser versions (and possible older apple hardware) having issues with Square website checkouts. I think any new Mac product/software does not seem to have issues with the Square checkout. Some solutions include having the customer clear their browser Cache/cookies, or use another browser. I've had to use Chrome as my browser on my older Mac laptop to successfully checkout on some Square run company websites.
