greenfire

Minetest doesn't send mods to the client it only sends information like a list of blocks registered by mods. The client doesn't execute any code sent to it by the server.

It isn't code is ran by the server and the client only sends information to the server about the current state of the client. This of course is sub-optimal as it can introduce a lot of lag to a game with mods that add vehicles or mobs

The server doesn't send code to the client, all mods are executed by the server. Server then send textures, models,etc to the client.