After updating my iMac Safari doesn't open some of my banking websites. What do I do?

There have recently been many reports of new problems with the latest release of v.15 Safari. It seems that the recent Safari update has varied issues. Word has it that Apple knows about the problems and is working on a fix. I assume that it will be released fairly soon. In the meantime, if necessary, you can use another browser such as Firefox or Chrome and they should work for you. Also, there are reports that reinstalling Safari and restarting the computer has resolved issues. 

The work arounds haven't worked for me - disabling javascript - I could not view this website. I would love to reinstall Safari as I have heard this has worked for a few people but I have yet to find instruction on how to do this.

Thank you for your advice. Contacted Apple Support and the tech, Gabriel, was really helpful. S15 is working...but really slow. Hopefully just temporary.