The major problem with OpenSea is the prevalence of NFT clones. As the prices of specific NFTs continue to get higher, more developers are minting NFTs that are a replica of popular ones. While this raises many ethical issues, the bottom line is that creators are losing funds to these clones. This prevalence of NFT theft has been ascribed to the lack of solid vetting systems for NFT creators on OpenSea. Compounding this, OpenSea does not require that NFTs be written on the blockchain before they are listed. This flaw is often exploited by users who seek to list stolen NFTs.
To combat this, OpenSea banned two NFT clone developers last year. However, there was considerable outrage, given that OpenSea is inherently a decentralized platform. Too many people in the crypto community, the ban amounted to censorship that only applied to centralized applications.