Just keep some buffer of generated tiles around the players, and either use a server to asynchronously decide on when which player moved to cause which tile to be generated.
You can also use something distributed if you go for peer-to-peer communication.
fix the seed and ensure everyone aggrees on the order in which they tell the generatoe that a certain chunk needs yo be fixed or should be freed from memory.
Consider just aggreeing on added/deleted blocks inside fixed intervals, and then process the list in e.g. coordinate order.
Consider Raft for peer-to-peer aggreement of the exact diff for the most recent period. Consider chunks of like 0.5 seconds per diff.
Don't apply the diff tk the generator until a moment later. You can interleave the cknsensus process of successive blocks a bit.