If you are not taking into account all the other work your team is doing, you are setting an unrealistic expectation of delivery for what your team is working on.
If the work they are doing is not accounted for in what they see, then they will feel stressed, then burnt out by all that is on their plate.
Sprint Capacities only work when your team is 100% only doing development work, as soon as they start doing other work, Sprint capacities become a much more trickier calculation.
