I found out a month or so ago that there is surprising reason why one must change the Apple ID password.
I used a US sim card last year when traveling in the US (I live in DE). The sim card was automatically deactivated and became obsolete after my vacation, so I got rid of it. That phone number continues to show up in my Apple ID profile under “Name, Telefonnummer…” and pops up on the receiver side when doing FaceTime calls.
I was not aware that in order to get rid of an obsolete phone number in the Apple ID profile one must deactivate iMessage and FaceTime for that “telephone” in the Apple ID profile, before the sim card is gone.
Apple support told me that now the only option to remove that phone number is to change my Apple ID password (yikes) and then deny whatever the system is asking me related to that phone number (something about whether I want to keep it or so pops up at some stage after changing the password).
The caveat is that I had to reconnect all my 10+ devices to iCloud (and whatever else) using the new password. This alone is a very ugly and time consuming process.
I did all that a month ago only to find out today that the phone number somehow reappears in my Apple ID profile. 
I have no idea why this number reappears.
I don’t want to invent yet another password (old ones cannot be reused, if they are younger than a year) and go through this lengthy process with all my devices again.
All my devices run the latest OS before 17.x and before macOS 14.
I know what Apple support sees as the only option, but I trust them only to a certain degree.
Any related suggestions or experience?