Cannot set up Gmail account to use aliases

Before iOS 14 i used a manually set up Gmail account on my iPad to send emails using my aliases. When there were problems with aliases with the initial release I accidentally deleted the account. I reverted to switching on email in my default Gmail account on the iPad but of course that cannot send an email alias. I have tried over a number of weeks to manually set up the Gmail account going through the “other” process. However i get an error message that the password does not exist or is wrong even though i am using the correct gmail password stating I should set it up in Mail Settings.

I had today when trying again, an alert from Google a less secure app was trying to access the Google account and was blocked. I clicked that “it was me” which should unblock. But still no luck

Any ideas appreciated