Loki needing to prune himself is kind of like Sylvie pruning herself near the end of season one to escape Renslayer and get to the Citadel at the End of Time. But he's not the one who prunes himself, and it's not Sylvie either -- whoever does it is behind him. Could this be another Loki? A Variant, or a time traveler? (Are those the same thing maybe?) In the trailer we do see Mobius talking with three Lokis. They don't look like Variants, though.