Something went wrong. Please try again, if this error persists try reloading the page.- error message - cant login on Firefox since 27th Mar

On firefox desktop browser keep getting this error message at the top and also same error message when one tries to login just after entering username & password -

"Something went wrong. Please try again, if this error persists try reloading the page" - so as a consequence cant login on to hotukdeals.com using Firefox since 27th Mar 2021

also the red 'Dismiss' bar that also appear on the right-side of the red bar doesnt go away ie when one click Dismiss it stays and the red bar stays as well.