How to get rid of annoying "fill code"???

I presume you're referring to the autofill for 2FA codes sent by email or text. Short of disabling the autofill entirely, no. Only Apple can fix it. To have Apple consider your feedback, submit it here:

Feedback - macOS - Apple

I also see this in some inappropriate text entry fields, and have reported it using the above link. A short (but not that short) time after the incoming code is deleted in Mail or Messages (I have mine set to automatically delete after use), the prompt ceases.

MattBieneman wrote:

So it is just fine for Apple to add "features" that mess up everyone's software except theirs? They should have some way to turn off these kind of annoying new "features". There is no way to turn it off, and it affects many third-party applications, so it needs to be reported as a bug.

Yes, it should be reported as a bug to the developers of the 3rd party apps where you see this happening. Apple releases beta versions for a reason, it’s the developers’ responsibility to ensure compatibility.

I am having fewer problems with 2fa code now than in December, so maybe some small changes were made by Apple, just guessing, or maybe I have figured out how to use it. It was not obvious to me that after putting the cursor in the target web page's fill code area, you can just hit enter, and the fill code rectangle would go away for good, along with populating the fill code area on the site. So for a good while I keyed in the code instead of hitting enter, and then found that the rectangle had not gone away. Instead, it would for example present itself near a spreadsheet cell that I had selected, even though I had already manually entered the code into the target web page code area. The same for a word processor. I use three non-Apple apps, but give me a more useful Pages and Numbers and Safari, and I would use them. Here is an analogy: When I buy a non-digital product, I often get a user guide. Shouldn't every software update come with a user guide, or at least a list of user-relevant changes? Maybe it does, but not easy to find, I think. If you can, please post the APPLE link that tells the user to hit enter to place the code in the box, and to make the rectangle go away totally. Maybe I just do not know where to look. Or maybe the philosophy is just to let the user figure it out the hard way.

Why would I need a 2FA code to post a message in a 3rd party messaging app? I wouldn't. I don't see this in macOS apps, and I suspect you're using a browser other than Safari. Not necessarily a macOS problem (given that it doesn't happen with native apps, at least for me), so would also be a good idea to provide feedback to the developer(s) of the app(s) where you see the 'inappropriate' 2FA autofill prompt.

aggieash wrote:

I can confirm this is happening on Chrome (v 143.0.7499.193). It keeps offering to enter codes from Messages in random fields (e.g., username, address, search, etc.). I HATE THIS! I will report to Apple feedback, but I hope they fix this or provide the ability to control this setting sooon.

You might want to let Google know, since they are the only ones that can provide an update to Chrome to fix the problem. As stated it does not do that using the Safari browser provided by Apple.

Brandnewuserid wrote:

The unwanted fill code appears in Libre Office Writer and in Calc. I use these third party apps only because in my view Pages and Numbers are not very good. Apple needs to modify at least Pages. Safari lacks a key feature too, in my view,but that is for another original post, off topic to go farther.

But let me ask this, from my non-technical point of view:

Why is this the third party app's problem, and not Apple's problem?

Because I don't have the problem with any apps. I use a few third-party apps, but not a lot. I have never received a request to use a code unless it is the app/website/wherever that requested it.

Using 'common sense', which software may ignore, the Apple 2fa box is the 'invader', and the third party app user is the 'victim'. OK, the third party app is on the Apple hardware, but I struggle to name any other 'interference' by Apple with a third party app being used, if the app is approved. I even bought Libre Office from the Apple store. Are we that really sure that the interfering 2fa code rectangle cannot be coded by Apple to appear on Apple apps only?

The app has to advertise to the OS that you have selected a field that is appropriate for a 2FA code that was just received. Your apps are telling the OS that it wants a 2FA code.

Pages User Guide for Mac - Apple Support

Numbers User Guide for Mac - Apple Support

Keynote User Guide for Mac - Apple Support

I've never read them. I just open up the app and use it.

Autofill security codes from your iPhone in Safari on Mac - Apple Support

If you and other users would get to work and report the problem as well, then maybe Apple would do something. Hopefully informing other uses will convince them to report it also.

As far as I can tell, there is nothing for me to report. It works exactly correct. The only difference is your improperly coded third-party apps.

The problem of the fill code for 2FA popping up in many inappropriate places, repeatedly, does occur on Firefox.

You should contact Mozilla, then.

It happens to me when I have Mac Mail in the background and it happens in ANY app - check out it here in Photoshop. On Tahoe 26.3.1. Also reported.

Please provide more details on "all kinds of inappropriate places."

The "fill code" only appears when I have selected the text field for entry of the 2FA code I just requested. It always only appears when I want it to.

Maybe I just don't understand what you mean as I have never seen it appear in any other context.

MattBieneman wrote:

The "fill code" appears, for example, in my web browser's "Search" field, and in my web browser's address field. This is entirely inappropriate.

Which browser? For me, in Safari, it only appears in code windows when requested.