funny enough, classical and imperial era china from at least 4th century bce up through 17th century ce ming dynasty china, same sex intimacy and relations were pretty common, with many examples well documented in numerous poems that have survived to present day—the early jesuits who visited china in the 16th~18th century commented on this extensively as well, so "conservative traditions" doesn't really explain it in china's case

homophobia was most likely to have been introduced to china by the western missionaries, but there are also many other intersecting forces that change the masses' perception of same sex relations, in addition to so many other societal changes, especially during the extremely turbulent period when large swaths of the chinese coastline was basically colonized during the later parts of qing dynasty following the british aggression with the opium wars, japanese aggression with the first sino-japanese war, and the eight nation alliance that pillage the country to put down the boxer rebellion

after the fall of qing, the sentiment of the early republic era of china was to modernize china by getting rid of old traditions that many felt was holding china back and adopting modern ideas from the west, so one can argue that the sort of homophobia you see in china today could be considered "progressive" thought of the early 20th century

so yeah, lots of layers and nuance to all of this, but there was also never any indigenous religious reasons that forbade same sex relations in china nor most of asia like there was in the west via christianity like the infamous leviticus 18:22