What if a contract returns different data when viewed off-chain vs during a transaction?

AdversarialRoyalties.sol

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

contract AdversarialRoyalties { 
    bytes4 private constant _INTERFACE_ID_ERC2981 = 0x2a55205a;

    function supportsInterface(bytes4 interfaceID) external pure returns (bool) {
        return interfaceID == _INTERFACE_ID_ERC2981;
    }

    function isEvaluatedOffchain() public view returns (bool) {
        return tx.origin == address(0)
            || tx.gasprice <= 1
            || gasleft() > 30_000_000;
    }

    function royaltyInfo(
        uint256 /* _tokenId */,
        uint256 _salePrice
    ) public view returns (
        address receiver,
        uint256 royaltyAmount
    ) {
        receiver = address(0xdEaD);
        royaltyAmount = isEvaluatedOffchain()
            ? 0               // looks like we're in getRoyaltyView(), so play nice
            : _salePrice - 1; // during an actual transaction, be nasty
    }
}

Based on this research:
https://karmacoma.notion.site/Detecting-we-re-evaluated-off-chain-aa5fb334f4e640aead68784ea065daf9