Modifying your render distance with the slider in video settings doesn't actually change how many chunks you see when in a multiplayer game (1.16.1)

The multiplayer render distance is controlled by server properties, so if you server has a render distance of only 10 chunks, changing your client render distance to more than that will not make any diference.

There is a known problem which doesn't seem to have a dedicated issue.
When you set your render distance lower than the server's setting, and use another mod to disable fog, Sodium will still render chunks to the full server side render distance.
A workaround for now is don't disable fog.

doesn't the game still render blocks that are behind fog tho?

By default yes, but fog occlusion should solve this, however it misbehaves with sodium if fog is entirely disabled