It’s not the strategy that stopped working (not like “oh, shit everyone is doing it and it’s tapped out”). FX carry used to work well due to the relationship in volatility of interest rates vs FX. It’s basically used to be a form of risk premium and now it’s gone, in part due to central bank policy, in part due to shifts in currency beta. Some people do it in EMFX, but that’s a very separate game, a true “close your eyes and cover your balls” type of trade.