The corresponding standard NFT API method is getContractMetadata
What does tokenType == UNKNOWN mean?
If this endpoint returns tokenType as UNKNOWN for any collection you query then it means that the smart contract for that collection probably doesn't conform with ERC721 or ERC1155 standards 100%.
Our Methodology: To deduce the tokenType, we run supportsInterface(erc721) and supportsInterface(erc1155) on the contract to see which one it supports. If it returns false for both, then the tokenType is marked unknown.