A problem repeatedly occured with

I cannot access an increasing number of websites through safari. I get the error message "A problem repeatedly occurred with "<url>"

I switched off the enable javascript options from Safari/Preferences/security and then re-enabled

I cleared the browsers history

I cleared the website data from Safari/Preferences/privacy

I reinstalled Mac OS to reinstall safari - I'm still on Catalina due to persistent problems running java apps on big sur and so cannot try the Safari technical preview

All the issues relate to websites with passwords - i.e. bank or credit card

Has anyone come across this please?