Oxygen level showing at 81%, but i have no problem?

Your finger is: probably cold or not getting enough blood flow, which then affects your PO2 measurement. If you are tracking your pulse oximetry, you should also see a sine wave indicative of your pulse pressure along with the O2 readout. If you do not, or do not have a machine capable of such reading, I would not trust your result. Thanks for trusting in HealthTap.