ERC1155 tokens from external sources may have different decimals, but they are not normalized to 18 decimals. The Ocean ledger takes whatever decimals it is and sets it to the corresponding shToken. For example, if a user wants to wrap an ERC1155 token that has 4 decimals, then they will mint a 4 decimal shToken.
The fee is therefore dependent on the amount of decimals that the ERC1155 token has. If a user wraps 100 tokens with 2 decimal places, eg 100e2, they can choose not to pay the fees by calling erc1155Unwrap 5 times instead of unwrapping 100e2 tokens directly. This is because the unwrapFeeDivisor has a minValue of 2000, so if the user can make the unwrapAmount less than 2000, then they will not need to pay the fees. (Instead of unwrapping 10000 tokens and paying 5 tokens as fee, user unwraps 2000 tokens 5 times).
