I have found that Google occasionally turn off the less secure apps flag on gmail accounts resulting in email notifications not being sent.
A better way seems to be:
Use a gmail account specially created for Node-Red rather than your main gmail account..
Turn on two factor authentication for the account.
Create an app password.
In the email node: Server smtp.gmail.com, Port 465, Use secure connection, Userid myraspberrypi@gmail.com, Password the 16 character app password generated above.
Of course if it's a problem with old versions of NR or the email node, it still won't work.
