What survives when you change phone?
The tags always survive, since they are plastic holding bytes. The routines survive only if they were never on the phone in the first place. That distinction is made when you build the first one and noticed years later when you replace it.
The tags survive
A tag is unaffected by a phone change. It holds what it held, reads the same, and needs nothing.
Unless it was locked it can be rewritten, and if it holds an address it may not even need that.
So the physical layer of your automations is the durable part, which is the opposite of what people expect when a phone dies.
What decides the rest
Routines configured inside an application on the phone go with the phone. Some applications offer a backup, and restoring one onto a different manufacturer's device frequently does not work.
Tags holding an address that acts carry on working immediately, because nothing about them lived on the phone.
Scenes in a home system are untouched, since the phone was only asking.
The pattern is consistent: whatever lived on the phone dies with the phone, and whatever lived elsewhere does not.
What a phone change involves
Finding every tag, which is the step nobody can do from memory after a year.
Working out what each one was supposed to do, which is harder than it sounds when the tag is blank and the routine is gone.
Rebuilding each routine, in an automation system that may work differently on the new device.
And testing each one, in the four states where routines fail.
Most people do two of these and abandon the rest, which is how a house ends up with tags nobody can identify.
What to do now
Write down which tag is where and what it does. One line each, kept somewhere you will find it.
Label the tags physically where you can, so an unidentified tag on a wall is at least identifiable.
Prefer addresses over phone side configuration for anything you intend to keep, accepting that it is more work to set up.
And never lock a tag used for a routine, so rebuilding always remains possible.
Frequently asked questions
Do I need new tags with a new phone?
No. Tags are unaffected and can be rewritten unless they were locked.
Will my routines transfer?
Only if they were not stored on the phone. Application backups exist and frequently fail across manufacturers.
What about home scenes?
Untouched, since they live in the home system and the phone was only asking for them.
What should I do today?
Write down which tag is where and what it does. It costs minutes now and hours later.