Why does my iPhone ask to join an old Wi-Fi network when setting up a new one?

By default and in my configuration, the UniFi controller sets all access points to broadcast all SSIDs on all frequencies (2.4, 5, 6 GHz). I am using the new U7 Pro XG access point.

According to https://support.apple.com/en-us/102285, the iPhone thinks that the SSID isn't broadcasting on all frequencies and tries to join another one on the 5Ghz frequency. This is totally the wrong thing to do. I have associated each SSIDs with a different VLANs.

I have confirmed that all SSIDs are being broadcast on the 3 different frequencies using my Android WiFi analyzer.

I can't see how any wireless device can have sufficient knowledge to decide that two different SSIDs are equivalent. In my humble opinion, Apple should not be asking this question.

I discussed this with a Ubiquiti support tech today and he couldn't explain what why Apple was presenting this question.

The moderator changed the title of my post to something that is incorrect. "iPhone asking to join additional network with a different SSID"

As I considered this further, my conclusion is that this is a poorly thought out "feature."

1. When a user specifies the SSID with which to connect, the computer/phone should do that. Don't try to second guess the user.
2. Yes, the computer/phone should try to connect with the Wi-Fi standard/frequencies that will be most performant for the given SSID just like Ethernet first tries to do 10Gbps, then falls back to 2.5Gbps, then 1Gbps, then even 100Mbps if required.
3. The Wi-Fi environment may block the 6GHz signal, maybe leading to the false impression that the SSID isn't available but somehow another SSID did show up on the 6GHz frequency. Would this trigger the "we can improve your overall experience message"?
4. The Wi-Fi environment changes as you move around a building. The SSID that that I wanted but the phone suggested not using, may be the better option 20 feet down the hall.
5. SSIDs with different names probably represent something different. Specifically, I have a associated SSID and VLAN pairs for my main network, another for my guest network, and a third for my IoT net. The phone suggesting to switch to the IoT net would be silly.
6. For my IoT network, I may choose to explicitly not enable the 6GHz frequency. Most all of today's devices don't support it and 6Ghz doesn't travel as far through walls, so why enable it? Does this choice trigger the iPhone to display the "hey, there's a better network" dialog when I try to connect to the IoT net to perform updates on my IoT devices?
7. I tried connecting between my various SSIDs on a Windows laptop, a Linux laptop and an Android phone. None of them displayed a dialog about choosing a different SSID. This seems to indicate that Apple is doing something nonstandard that, in my opinion, is bad.

I did submit a bug report to Apple.