Turn off Facebook Messenger option in the Location Services. To do that, go to Settings, tap on Privacy, and choose Location Services. Find Facebook Messenger, and toggle the switch to turn the option off.
Another thing you may want to try is turning off Background app refresh for the app. To do that, go to Settings > General > Background App Refresh. Find Facebook Messenger on the list, and turn it off. Hopefully, it will solve the problem.
All kinds of issues are possible if the app is not up to date. Go to the App Store, and see if there is an update available.
If there is a new version of iOS, make sure to download it and install it. Upgrading your iPhone is always a good idea because it can fix all kinds of bugs.
Backup the important data. Go to Settings > General > Reset > Erase all Content and Settings. You will reset your phone to the factory settings, and you will set up your device as new.