Socialist governments must redistribute, come hell or high water, and the decline of production turns out to be hell and high water. If you take away an incentive to work and produce, you end up taking away the producers. Visitors to the Soviet Union remember trying to get the attention of a waiter in a restaurant: why should anyone help if there was no reward for helping? There is a health crisis now within Europe as doctors flee poorer member states in search of better pay in wealthier member states, and in the UK, fewer people are applying to medical school. This realization is why Margaret Thatcher is quoted as saying, "the problem with socialism is that eventually you run out of other people's money."
Socialist governments have a monetary solution to that problem: they just print more money. That works for the moment, but from then on, inflation increases until all money becomes effectively worthless and one cannot buy any goods or services, if there were any to buy, which by then usually there aren't. Inflation in oil-rich Venezuela reached 80,000% in 2018, according to Forbes. Socialist "equality" becomes equal poverty and starvation for all, except perhaps a few in government.