I open TOR with a bridge to a foreign country. During use when I opened a new tab the bridge switched to USA. I never saw this happen before. Is it suspicious or normal activity?
This sounds normal. When you set up a bridge, you add more than 1 bridge to the Tor Browser. For whatever reason, Tor decided to use one of the other bridges instead. There are any number of reasons why Tor would use a different bridge. Maybe it was just time to refresh which bridge was in use, similar to how Tor chooses new guards after a period of time.