My banking website went into jailbreak and cannot sign in

In addition to these other suggestions, Go into safe mode. If it works correctly there, you'll know you have something installed that is affecting you when you login regularly.

But....yes......more details please!

Start up your Mac in safe mode - Apple Support

What do you mean by "jailbrake". It sounds like something you need o talk to the bank about.

What did the bank IT people say about compabitiliy with Mac systems?

Have you tried with other browsers? Firefox, Brave, Opera ……

You’ll have to explain that and many more details