That sound like a configuration issue with your wireless carrier not an Apple issue. Some wireless carriers go out of their way trying to force you on their native network even if it does not exist in your current location.
I would agree with you but the back and forth dance I described has been like that for years now. From my trusty old iPhone 7 (when we could have roaming data on my country) to my XS max today.
So it's not a problem related to my phone, nor to my carrier because I changed several times since then.
My phone has been bought unlocked and I have a plan that allows me to do whatever I want freely (my colleagues on Android don't have this issue).
The cellular stack in iPhones has always been written by psychotic interns as far as I know.
The thing is, until recent versions, US customers had different radio. We were privileged to get the first Intel radios, and it has been a mess since then.
My kids have the SE2 with Qualcomm chips and it's already much better. That being said the dance still is the same, you just get a faster list of carriers. It also rotates quicker so it's also a worse troll.
I spare you all the steps I've gone through to try to fix this, all kinds of resets and reinstall, nothing changed.
That's why I'm pretty sure this is just bad design and terrible coding done by people never leaving their comfy offices at Cupertino.