The current version of the FlowNFTDescriptor contract responsible for the metadata JSON does not include the protocol fee as part of the metadata. However a future version of the NFTDescriptor can include the protocol fee and therefore a change of the fee should emit a BatchMetadataUpdate event so third parties can update the metadata accordingly. EIP-4906 also specifies that it MUST be emitted in this case.
The MetadataUpdate or BatchMetadataUpdate event MUST be emitted when the JSON metadata of a token, or a consecutive range of tokens, is changed.
From Cantina finding 13
The current version of the
FlowNFTDescriptorcontract responsible for the metadata JSON does not include the protocol fee as part of the metadata. However a future version of theNFTDescriptorcan include the protocol fee and therefore a change of the fee should emit aBatchMetadataUpdateevent so third parties can update the metadata accordingly. EIP-4906 also specifies that it MUST be emitted in this case.The
MetadataUpdateorBatchMetadataUpdateevent MUST be emitted when the JSON metadata of a token, or a consecutive range of tokens, is changed.