Unfortunately, your browser is unsupported...Safari Version 14.1.2

[merefield (Robert)]

About support for legacy browsers

They aren’t. Our official browser support policy is the latest version of Firefox, Chrome, Safari and Edge.

and more specifically:

Unsupported browser message on Snap! forums

Yes exactly - we’re using the lack of aspect-ratio as a way to detect older browsers. There are other, more critical, things we now using (e.g. the optional chaining operator) which tend to be unsupported on browsers which do not support aspect-ratio. Our list of supported browsers can be found here. We currently supports iOS 15.7 and above (which is supported on Apple hardware released from 2015 onwards).

Which suggests you might get away with >=15.7 on macOS