A friend suggested that social energy is drawn from a finite reservoir, and that once expended it can take some time to fill back up. If that reservoir is fully emptied then it could perhaps result, at least for certain introverted types, in fatigue, ambiguous smudgy-greyness, or a bad case of The Grumps. Sage advice.
During lockdown reservoirs of social energy have undergone seismic shifts in the proverbial water table. Some may have been perpetually overdrawn by cabin-fever children, or be entirely full to brimming, or else have strangely receded from lack of use, leaving less to begin with.
So, be gentle with each other.