It seems that you are experiencing an issue where the bot app automatically enters and cannot be exited in the Teams app on iOS. This issue has been reported by other users as well. One workaround that has been suggested is to swipe up from the bottom of the screen to open the app switcher, and then swipe up on the Teams app to force close it. Another workaround is to uninstall and reinstall the Teams app. If these workarounds do not resolve the issue, you may want to contact Microsoft support for further assistance.
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