Open interest across EUA futures contracts has largely followed consistent, traceable patterns through the operation of the EU ETS. The energy crisis and the reform of the EU ETS has shaken some of those trends. The shifting landscape shows the power sector reacting to the aftermath of the price instability caused by the Russian invasion of Ukraine and to rapid regulatory steering towards decarbonization. Additionally, participant behaviour shows a limited reaction to the changing compliance schedule as adjusted by the EU ETS reforms. Falling open interest across all contracts may point to increasing liquidity risk for the EU ETS, potentially increasing price volatility and harming market functioning.