The scholars agree that it is permissible for men and women to cover the face during the prayer.
To wear medical masks which cover the mouth and nose during the prayer to protect yourself from air borne infectious diseases.
Ibn ˁAbd Al-Barr said, “They (The scholars) have unanimously agreed that the woman uncovers her face in prayer and ihram; where covering the face will prevent the direct contact of the forehead and nose with the ground and also covers the mouth.”
The prophet (PBUH) forbade men to do this. Whereas, if there are strange men, it is permissible for the woman to cover it. The same case applies to the man; it is permissible for him (to cover it) if there is an actual need for this.