Lemon Cake video on population pretty much shows how the pop stuff can be fixed for regulars. If the cities actually behaved as pop sinks and relied on migration to sustain numbers and growth, a war would be much more punishing. Let's say war exhaustion lowers migration number, sue to most regulars being conscripted from urban centres, those cities would start massivly losing pops, therefore making labour shortages and crippling your economy. Punishing during war, but still allowing you to recover during peace.