AirTags not updating location after iPhone travels to Canada

I have tried every "10 things to try when your airtag is not working." but nothing works. I have 4 airtags in 4 vehicles in North Dakota that used to update location up to the minutes just fine, all the time. On December 2nd I flew to Vancouver BC (of course without any of the vehicles), and since then the location is not updating on my iPhone 14 pro max. I'm with Verizon prepaid if that matters, and the phone works fine there, it's just that none of the 4 airtags were updating

2 weeks later I flew back from Canada to the US on December 18th, still the "Find My" app is not updating airtag locations. I've reset network many times, still not working. Now it's January 9th and it shows the airtags were last seen 2 months ago. I feel my problem has a lot to do with my iPhone being in Canada for 2 weeks. What do I do now?

[Re-Titled by Moderator]