I've flown on half a dozen different airlines this year and all have had exactly the same stance: no power banks in checked luggage, and if they're in hand luggage you must be able to see them at all times (not in overhead storage).
You're also not allowed to use them even if you do have them with you. This is all very strictly enforced with reminders at the check-in desk and several announcements before take-off.
You're also not allowed to use them even if you do have them with you. This is all very strictly enforced with reminders at the check-in desk and several announcements before take-off.