my dad's airtag connected to his phone just fine until he lent it to my uncle and it worked for my uncle's apple phone but now it won't connect back to my dad's phone (or any phone, it's not recognized at all) even after it disconnected from my uncle's phone. we all have updated iphones.
[Re-Titled by Moderator]
iPhone 11, iOS 18
Apple AirTags are associated to a user's Apple Account, not to their iPhones. It would be safe to assume that your uncle has a different Apple Account than your dad's ... at least, he should!
So, if he was able to "pair" it with his iPhone, then at some point your dad would have to remove the tag from his account, so that your uncle can add it to his
Then before he gave it back, he would have had to reverse that process so that your dad could use it.
Alternately, your dad could have also "shared" this tag with his brother.
Ref: Share an AirTag or other item in Find My on iPhone - Apple Support
AirTag not connecting to original iPhone
