Terrible support, and Apple is also responsible for building Safari into the OS.
Terrible support for a terrible website, no surprise.
Website developers that intend to use Safari need to develop for Safari. Apple does not develop websites, other than Apple's websites.
Chase Bank needs to stop using the outdated and privacy-intrusive "user agent" query as the means to determine if a browser can handle their website, which was never a good idea to begin with. They are the only large commercial institution still doing that.
If you are motivated to do so direct their attention to this excerpt from Apple's Safari Developer Documentation (emphasis added):
Important
Use feature detection to enable or disable functionality instead of relying on the name or version of the browser in the User Agent string. Learn how to detect available features on MDN…
The passage regarding feature detection in that document uses even stronger language:
"... this is a terrible practice that should be discouraged at all costs."
Unfortunately, Chase's continued and inexcusable use of that terrible practice leaves you out in the cold until they realize the error of their ways and correct it. Contact them and ask if they would like to purchase a new Mac for you, or if you should continue to indulge their terrible practice by using a different browser. Choose one, or the other.
Or, they can fix their website, like everyone else already did years ago.
