As of this writing, v5.6.2 is not "officially" released, but it is available to download for everyone. v5.6.2 is now officially released
It's the 11th hour of Oauth2 for Gmail being deactivated. This update will allow you to continue using Gmail/Oauth2 by creating your own Dev credentials. The process is pretty easy (with instructions) and should only take about 5-10 minutes.
I think that this method may be the preferred method not just for anyone who doesn't want to enable 2FA, but it may be easier for people who have at least a couple Gmail accounts not already setup to use 2FA.
Here are the instructions:
https://www.esumsoft.com/pop-peeper/faq ... thPrivate/