You can try to change your Firefox version number. This might fool their site. Here's how:

1. In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.
2. In the search box in the page, type or paste forceVersion and pause while the list is filtered
3. Double-click the network.http.useragent.forceVersion preference to display an editing field, and change the value to 128 or 140 then press Enter/Return or click the blue check mark button to save the change.

Does it work? Please report back to us!

I have Windows 7 Pro, PC...Love it!....and Firefox Browser...have up dated also... Chase Visa will NOT recognize my Friefox Browser and let ME LOG IN(Nothing below an 8.1 system) HELP!

Since you are using the old eol Windows 7 the most current version of Firefox you can run is Firefox 115 ESR currently at 115.30.esr which you appear to have. Firefox 116.0 and later requires Windows 10, 11 and macOS 10.15+ and Linux to run. https://support.mozilla.org/en-US/kb/firefox-users-windows-7-8-and-81-moving-extended-support

According to this thread /questions/1547075 the Chase site is looking for Firefox 138.0 or later. So either you can try the trick above as Firefox 140 or the the more technical way is to dual boot with a current version of a Linux distro.