Since the latest update, I am unable to send any email from my two linked gmail accounts for the last month. Every single time I get a SMTP error and the email gets stuck in the outbox. I already tried to remove and re-add the accounts but still the same issue.
If it is not fixed after 10 years, it is time to move on to an email client that can at least send an email. It is not like Google is some random account.
Can you copy the full error and ideally also the relevant part from the Operations>Log window?
Just check it right after a sending fails and copy the full log connected to Gmail SMTP.
You can censor the emails of course, but without the actual error we can’t really guess what the issue might be in this case. I tried to replicate the issue on the same version with multiple Gmail accounts and was not able to.