Its not really a bug but a side effect of how the transformer is programmed. it seems when machines power demand fluctuates, the transformer lags behind to output more power to meet satisfaction. This causes lights and nixie tubes to flicker on and off.

one suggestion ive thought of, is instead of constantly trying to match the output to meet satisfaction, causing the fluctuation, a transformer should be capable of remembering a Max Satisfaction, and constantly output that, reset on a set time (like every 60 ticks, or ingame day) this way, if a machine turns on and suddenly needs 50MW and the network passively drains 10MW being idle, it doesnt cause everything to quickly loose power as the transformer quicky tried to meet demand.

An alternative solution may be to always multiply the demanded power by 10% so there is always a surplus of power in the surplus network. This wouldn't be an issue in small bases, but in megabase this would become a significant higher demand. (100MW would be 110MW. compared to 10GW would be 11GW)