What caused it?
It is likely a disorder of hair follicle occlusion and directly related to increased duration of mask wear :

• Mechanical stress due to pressure and friction
• Microbiome imbalance due to heat, pH and moisture
• Tropical climates and outdoor exposure (increased sweating) are risk factors for acne-susceptible populations
   

How to manage?
Special consideration for skin care should include:

• To wash the face 2 times a day with gentle cleansers
• To apply oil-controlling moisturizers
• To avoid strong products with salicylic acid, sulfur, α-hydroxy acids, and retinoids that could predispose to irritant contact dermatitis under occlusion
• To wear light make up or avoid make up
• To visit dermatologist for severe conditions