Despite its client-side only effects, using the mod will render you unable to play alongside Vanilla players.

[SplachiFrenchSquid]

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Title is self-explanatory, cannot join Vanilla players lobby while using the mod while it's effects are purely client-sided, which a bunch of other mods have no problem with. Using a function similar LC_API's "EnableNetworking" option could be a potential way to adress this issue.