Some listings on Uniswap will have a red caution sign next to the NFT ID.
A red caution sign means that the NFT was reported for suspicious activity on OpenSea.
The transaction review screen will warn you before you make a purchase if an NFT is marked for suspicious activity on OpenSea.
Please get in touch with the Uniswap Labs support team if you unknowingly purchased a marked listing on Uniswap.
Updated