The bug

Since 20w21a, strongholds don't generate in Bamboo Jungles and Bamboo Jungle Hills in the Overworld. This only affect "normal" worlds, strongholds still generate in single-biome worlds or worlds with other custom biome generation.

An affected stronghold can be found in seed 14916203336864, at coordinates [-10000, 4384] (see attached screens). Notice that the stronghold is present in 20w20b, but has moved ~80 blocks in later versions so that the starting point isn't in a Bamboo Jungle biome anymore.

This is probably caused by the POSSIBLE_BIOMES list in OverworldBiomeSource missing the Bamboo Jungle (Hills) biomes.