Why has inflation declined as a trend in the euro zone?

When we look at core inflation in the euro zone, we see that it is on average: 2.7% per year in the 1990s; 1.8% per year in the 2000s before the subprime crisis; 1.2% per year in the 2010s prior to the COVID crisis; 1% per year today on average. What accounts for this trend decline in inflation, which is now putting monetary policy in difficulty? Not a monetary mechanism: the money supply has rather accelerated over this period; Not higher productivity gains, because they are on the contrary declining; Increased competition from emerging countries; Employees' loss of bargaining power. When we look at wage formation over these different periods, we see a very significant decline over time in the effect of the unemployment rate on wage growth in the euro zone.