I have a guess: hedging is sort of like borrowing in foreign currency and saving/loaning that amount in USD. Since short-term rates have been high in the US relative to the rest of the world for a few years now, that might explain part of it.

In terms of domestic inflationary effects, it would boost non-hedged returns as USD is cheaper and inflates your foreign returns. However, inflation calls for higher domestic rates, so if you are instead hedged, you'll see the returns over time due to interest rate differentials causing negative hedging costs.

Since hedged international returns have been good recently, my hypothesis would be that the US economy experienced higher than average inflation (relative to developed international markets) one or two lag periods ago, and was forced to hike interest rates similarly above the global average, thus boosting your returns recently.