Private Address turned off by itself on 5Ghz home network

Hello,

I am iPhone XS user. Since I really care about my privacy and safety of my home network, I just wanted to ask a situation that happened me last night. My router is Xiaomi Mi Router 4A.

Last night, I was at my living room, this room is far away from router so, 5ghz is very slow while I am in this room. Because of this I generally keep wifi off at there use my mobile data. After I leave my living room and get near to router, I have turned off my mobile and opened wifi to connect 5ghz, It automatically connected my 5ghz wifi however, as first time I saw there is a privacy warning under my 5ghz wifi name, I clicked on WiFi and saw that it was stating my private address is turned off. I have checked the private address setting and It was really turned off by itself. I didn't turned it off and it was on same day's morning. Immediately I have checked my 2.4Ghz and the setting was still turned on, there wasn't any problem. Switched back to 5ghz it was still turned off and I turned on myself and the warning is gone.

So my question is, why this happened, why the settings turned itself off , on my 5GHz network?

Also I can say that this network was known by my device before iOS 14 install, so according to this article it's a previously-known network.

About private Wi-Fi addresses and enterprise networks - Apple Support