my OS is Sonoma and I can't get into my credit card website using Safari only Foxfire

You're not doing anything wrong. Chase Bank is, by using an outdated method of determining browser capability. Contact them and tell them to fix it. When you do, 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 use of that terrible practice leaves you out in the cold until they realize the error of their ways and correct it.

The workaround for end users who are unable to update their Macs to a newer macOS version is to use a different browser.

Consider Brave:

https://brave.com/

Firefox is a distant second choice:

https://www.mozilla.org/en-US/firefox/new/

The bottom line is that there is nothing wrong with your Mac's version of Safari, but that bank is using an outdated and ill-conceived method of determining browser requirements.

One thing to try. Go to Safari menu > Clear History (or if you don't want to clear all history go to Safari menu > Settings > Privacy > Manage Website Data and search for the leading characters of the bank name and remove website data related to the bank). Then restart Safari and try logging into the bank.

Or it may just be an issue with the bank (Chase and Citibank both work with Safari for me)