In addition to my Dovecot issues, postfix as well had failed and I wasn’t able to send emails. However, getting them was more important at that point.
After some trials, I found I needed to add this to my main.cf
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
Which has resolved postfix from not working. Hopefully I fixed all my issues since my upgrade.