OpenSea announced yesterday their new system that "proactively scans URLs shared on OpenSea to identify if they may be malicious. It starts by cross checking a given URL against a blocklist of known malicious sites." OS noted that "scammers ... try to spread these URLs on OpenSea through fraudulent collection listings and unwanted NFT transfers." According to OS, the new system also "analyzes interactions and transactions to identify malicious behaviors like signature farming and wallet draining"OS will "simulate interactions and transactions with new URLs to identify malicious behaviors like signature farming and wallet draining ... Scammers that attempt to spread detected malicious links will have their accounts banned, their collections delisted, and their transfer requests blocked when using OpenSea." Under this new pilot program, OS will try to "detect NFT theft in REAL-TIME and prevent further resales of suspected stolen items to unsuspecting buyers." OS will then display a new yellow “under review” module on those items. According to OS, this move is to better address the ongoing problem of thieves reselling NFTs before victims have an opportunity to file a theft report. 

OS tweeted that "items involved in detected suspicious behavior will be temporarily disabled on OpenSea, and the previous owner will immediately be notified via email. The previous owner can then share feedback with us to reinstate the item and enable it to be sold again." Most importantly, OS announced that they are "working closely with other marketplaces, wallet providers, analytics organizations, and others, to develop holistic scam detection and prevention systems."
These measures by OS look like a good step in the direction of trying to address the issue of stolen and flagged NFTs. But, without cross-platform adoption of these measures, flagged NFTs continue to be bought and sold on other NFT secondary trading marketplaces. 
It will be interesting to see how this program works in real-time, whether it will curb the continued market for flagged NFTs and whether other platforms will agree to adopt similar measures.