I'm not surprised to see Opensea valuations drop. We are in a bear market, the money flow is being blocked.
The NFT market is becoming much quieter than before. Perhaps more efforts will be needed to improve technology and user attraction policies. There are more competing platforms and that's a barrier for Opensea.
They are facing competition they did not had before, while the bull market is still far away and there is also some skepticism towards NFTs which was not there before, so it is reasonable that OpenSea is facing some issues as they no longer have all the circumstances on their favor as they did some time ago, can they return back to their previous glory? This is difficult to know as I doubt that NFTs will attract the same attention they attracted before as simply too many people lost money with them.