Depends on the office,
@Mic****
. My previous COVID extension expires in February, but after applying at Phuket this week the office called me to inform me that I was going to lose days. "Why did you apply early? Now you will only get 30 days." 😆
People in Bangkok, Samui, Chiang Mai, etc, are receiving the full 60 days, counted from the expiration of their previous extension of stay.