Latest Update 151.0.1 has broken TOTP

Do you mean specifically any TOTP authentication on any and every site, or you're having issues with logging into just one specific site? (Which site, or provider is that?)

Further testing revealed it seems to be just unifi.ui.com . I have now checked at least 4 other sites and all ok. I have reached out to Unifi support for further advice.

Unifi report no issues reported at their end - I have tried a new Firefox profile , still no change. Any ideas of where I can further fault find within Firefox , any new security features that may have broken TOTP.?? Any logs I can check .??

I also don't see any compatibility breakage for account.ui.com or unifi.ui.com reported per se regarding the MFA failing to pass — only more severe rendering issues potentially resolved by lowering Enhanced Tracking Protection settings.

You mention clean profile — that should rule out any stale session data. Could you also try restarting in Troubleshooting Mode to see if it makes any difference? Thanks.

As for logging, it might be worth checking devtools, if there's any "red" codes in the Network pane, esp. if there are some async hits around the TOTP invocation or submit (any 400– or 500– series codes with errors for some endpoints).

Apologies , To clarify , I normally use my Ubikey for account.ui.com , I have since tried TOTP and it works Ok. The error occurs when I am logging into my local Unifi Router using Ngnix Proxy Manager , the Network Panel shows NS_ERROR_WEBSOCKET_CONNECTION_REFUSED when entering TOTP code. I have since tried entering the same TOTP code twice and it works on 2nd entry every time. The local login is obviously validating against account.ui.com , seems to be a timing , delay issue.???

And the WS connection is both to the same endpoint? Is that perhaps… a local access, that might need allowing now? Control personal device and local network permissions in Firefox