Is there كراهة in wearing a face mask while performing Salah?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
Covering the face in prayer differs according to the circumstance of the individual. For men, it is disliked based on the Hadith of Sunan Abu Dawud and others. The Prophet (SAW) prohibited men from covering their faces in prayer. However, if there is a valid reason such as a medical reason, then it will not be disliked in that case.
As for women, it is strongly disliked for them to keep their faces uncovered, especially if the girl is young and has a greater fear of fitnah. However, if the woman is old and does not fear fitnah of on-lookers, then it will not be disliked for her to pray without a face covering.
Only Allah knows best
Written by Maulana Nabil Khan
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Sunan Abi Dawud #643
 Radd Al-Muhtar Volume 2 pg 81