Two factors Authentication forced with the new update without my approval

You did approve it during the restart process after the update as part of the setup procedure. Apple just makes telling it not to update to 2FA somewhat difficult to find. It is usually in small letters in the bottom as something such as "other options" when you update. You just told it to "continue".

If you only did this recently you have two weeks to undo it using the information in the email Apple sends you. More information here --> Two-factor authentication for Apple Account - Apple Support

For most services, 2FA is required. When it is turned on, you will see an email confirmation and since you reference having another device, is it possible that it is used by someone else who turned it on after attempting to use a service that required it? For any new Apple Account, you do not have a choice and must use 2FA, and for older accounts I have seen no reports where iOS 18.6.2 turned it on automatically.

Apple makes it clear here:

If your Apple Account was created using two-factor authentication, this extra protection can’t be removed. If you recently enabled two-factor authentication, you have the option to lower your account security within two weeks of enrollment.

Two-factor authentication for Apple Account - Apple Support

The removal in the 2 week period was only possible from the email link sent to you when 2FA was turned on.

You can not disable two factor authentication. That's not my "opinion". It's a fact.

I'm sorry if you don't like it, but that's the way it is. This is a user forum. We are not Apple. We can't change it.

Many of us will be happy to help you transition to 2FA.

It’s “a big nothing burger” from a general user perspective but it should encourage you to “tune up” your Disaster Recovery Plan.

Suggest review these three articles; paying particularly close attention to Trusted Numbers.

Two-factor authentication for Apple Account - Apple Support

About trusted phone numbers and trusted devices for Apple Account - Apple Support

Get a verification code and sign in with two-factor authentication - Apple Support

Limnos wrote:

You did approve it during the restart process after the update as part of the setup procedure.

I just about suggested you as a good source for confirmation on whether the update turned on 2FA, because I believe some of your previous posts mentioned you did not have it on and was using Security Questions.

I did not want to speak for you, but glad you chimed in here.

Computer, most definitely you can avoid 2FA.

iOS I am 99% certain you can.

My iPhone tops out at iOS 16, but I did recently update my computer and my wife's computer to 15.6.1 and the menu options did lead you to update to 2FA unless you happened to notice the small button that I think said "other options". I also helped my wife when she last had to update iOS on her iPhone 16e so I probably walked her past the 2FA pitfall when updating. Apple just does their best to make it not-obvious. You have to read things carefully. I know each time I sign into the forum here I have to click once to enter my Apple ID, a second time to enter my password. It then asks me if I want to upgrade to 2FA or "other options". When I click "other options", of course one of the "other options" is also to upgrade anyway and the other is don't upgrade. Not sure why Apple doesn't just ask, "Are you really sure you don't want to?" Makes signing into ASC a real chore and the 4 clicks are not something to be done before my morning coffee!

I don't use 2FA because one critical scenario is using my iPhone as an iPod Touch on trips to other countries. I may not have phone service, wi-fi is sporadic (but important to me when I do get it), and I have no other Apple devices with me. Should I need to get a code, having Apple call my landline or send a code to my computer at home does me no good, nor can I easily contact others who might get a code for me. I don't use any of the services requiring 2FA. I have no app or media stores purchases. What I use my account for is basic sign-in for OS updates and to post on this forum.

Are you in the US? Every other country has Apple 2FA mandated, for good reason.

I was not aware 18.6.2 changed the requirement. Anyone?

So to be clear …

… is it still possible to update to 18.6.2 while continuing to “opt out” of 2FA ?