Hey Guys,
So I think I found a solution that seems to work. I upgraded tokay to iOS 14.0.1, thinking that they would have fixed the issue, but the test email I sent continued to come from @icloud.com. Then when I went to the Mail settings, I noticed that all the other aliases had the Allow Sending From as ON. The description of the option reads the following:
"Choose which addresses you would like to use when sending from your iCloud account. You will still receive mail at all of the addresses above."
That led me to go and toggle all aliases [non @mac.com] to OFF. That did the trick! The emails are sent from @mac.com and based on the description above, and you will still get emails for the other aliases. I hope this helps.