The flag at half mast on top of the WH happens anytime the President decides the occasion warrants it. Without an explanation from Trump why he had it lowered we have no concrete answer to why it was lowered. He'll with everything going on we can't even be certain Trump was actually behind the lowering of the flag or if someone else ordered it down and forced the soldiers to comply. It could be because of what happened at the capital and those who died, or it could be because the constitution was officially killed this past week, or like this person it could be a sign Trump is taking action via IA. Without an explanation its impossible to know for certain.