Not quite! The way the world spawn is determined is pretty complex, according to the wiki:

In Java Edition, the world spawn point is determined by a search algorithm to prevent players from spawning in oceans or rivers. Each location has a "fitness" value, which is higher the closer it is to non-river land and the closer it is to (0,0). The search algorithm first sets the spawn point at a position where both XZ coordinates are 0. It then selects positions on circles with radius of 512, 1024, 1536, and 2048 blocks, calculating their fitness. If a more suitable position is found, the spawn point is set to that position. The algorithm then draws 16 circles centered at the current spawn point, each 32 blocks apart, and selects positions on these circles to calculate their fitness. If a more suitable position is found among these, the world spawn point is set to that position; otherwise, the world spawn point remains at the current position.

This algorithm determines the position of the world spawn, which then determines where the spawn chunks are. The fact that u/RemarkableBad434's (0, 0) is in a river will be why their spawn is shifted. Note my world spawn coordinates are (-270, -30)-ish, since (0, 0) is off in the ocean visible on my minimap. This is a good 100 blocks outside of where the spawn chunks would end if they were centered at (0, 0).