The lag always happens for the people who join the game. It only happens to online games but playing locally is fine. We have tried being on separate connections, and playing with different 4 different hosts. Realms seem to be working fine. Will also some times get unable to load world when trying to join or it will take a while to join and for assets to load.
Lagging includes being thrown around, glitching through floors, invisible blocks after seemingly breaking them. The host can see the guest playing but it's way behind what is happening in real time. Example: I'm (guest) halfway up a mountain but the host looks over at me and I'm still at the base. Or I'm placing down blocks but the host sees that some blocks are missing.
All on switch consoles. We've tried 4 different internet connections. 4 different Nintendo /Microsoft accounts (same shared family switch online account).
Yeah, this is a REALLY bad issue. Joining a multiplayer game-especially one with more than 2 players-can lead to SUCH BAD LAG. For example, say it's a Sunday morning. Your brothers are playing Minecraft on the couch; One on Nintendo switch, and one on a tablet. You have your tablet nearby, so you join them. You start to play, but the world starts acting up. Full on lagging back to an area you were in 3 minutes ago, killing animals when no one touched them or used commands, teleporting is just wrong, and if someone tries to swim, everyone teleports to a far off place, it's insane. Mojang, Please fix multi-player!!