It will affect those apps that you gave permission to use your gmail account (which generally is a bad idea to allow). I figured I would find out which ones I needed when they didn't work, so I turned it off. You can actually find a list of which apps you gave permissions to, somewhere, I think...

App access is also something that you can create when you need to send GMail from an application (e.g., emailing yourself errors from an app). You create an App password and use that for sending from an app without having to do 2FA, which would be tough to do from an app.

Hank

>Hi,
>
>I have a couple of gmail email accounts. In the past few days I received emails from Google regarding each of these accounts. The email refers to "2-minute check up .. the actions should take to make your account more secure" (attached image 1)
>
>Then when I click on the Take Action button it brings me to the page (attached image 2).
>
>I see 1 "issue": Third-party access. Turn off less secure app access. When I click on this link it brings me to the next page (image 3)
>
>And here is my confusion. If I click on TURN OFF button, will it affect my access to gmail email from iPhone and iPad? I don't understand what they (Google) mean by "less secure app access".
>
>Anybody had this experience? If yes, did you clicked on TURN OFF?
>
>TIA