Robbie Ferguson, co-founder of Immutable X, said on Twitter that "NFT royalties on Immutable X are guaranteed," and marketplaces and creators can have protected ongoing monetization on any marketplace assets trade. He added that NFT royalties are enforced on any marketplace at a protocol-wide level, which means "marketplaces aren't forced to compete by offering optional royalties, but can have guaranteed economics."
Previously, Magic Eden announced that it started using optional royalties.