Spawns have changed in version 1.21.2 and 1.21.3. I've noticed this on island seeds specifically - some have the same spawn point as 1.21 but some spawn you far away on the "mainland." Spawns for other seeds may have shifted too, I have not gotten to testing those yet. So - some seeds have the same spawn location as 1.21 but many do not.

An example is this seed: 2003140362

Since 1.18, Cubiomes Viewer shows the island in the middle of an ocean being the spawn point at coordinates 16,16:

However, in 1.21.2, this spawn point has changed. As seen on Chunkbase:

And in game at coordinates 70, -1142: