There are millions of NFTs across the different blockchains that Moralis supports. The vast majority of NFTs never change metadata, therefore Moralis doesn't automatically re-sync metadata. This is something we may do in the future!
For now, Moralis has the Resync metadata endpoint that can help you manually trigger metadata re-sync on the specific NFT. We know that this feature is important when you develop your NFT and you may be experimenting with different metadata and updating it often during the development of your app.
Join our Discord to be updated when this feature is released!
If you want us to add the auto re-sync feature - add it or upvote it here: https://roadmap.moralis.io/b/feature-requests/