When a liquid body (i.e. aquifer or lava pool) intersects a monster room (dungeon) on a chunk border, the liquid does not flow into the monster room. I'm unsure whether this also occurs with springs but it would not surprise me if it does.

Note: use 24w34a or later, there is no monster room here in 1.21.1.

Seed: -7791476409053505400
Coordinates: /execute in minecraft:overworld run teleport @s -2100 -31 30619 23 -6

For comparison, there is another monster room nearby (/execute in minecraft:overworld run teleport @s -1892 -47 30771 180 0) into which water flows correctly because there is not a chunk boundary in between.