What's the most common issue you encounter when using Antminer？
heat and noise on the s21 and s19 models
they pull 3300 watts and are loud.
those two things will be certain enough.
next is break down of gear.
break down of gear is at least 10% per year.
if you have a lot of them there is almost always one or two that suck.
The s21 XP model is better though and more effective and efficient but as you stated earlier on it's power consumption, the XP consumes 3645 W of power which is massive as well. It has 270 Terahashes per second. Since it's flaw is the high rate of electricity that it consumes, it's suitable in countries where energy cost are lower and I believe if people from these kind of countries has this improved models, they will mine more than when using the older model of just s21.