Using entity instances in EF Core queries can definitely be convenient, but it comes with a few trade-offs that are worth considering. For one, it might lead EF Core to pull in extra data or add unnecessary joins, which can slow things down—especially with larger datasets. Another thing to keep in mind is that the generated SQL can become a bit more complex and harder to read, which can make debugging a hassle. Plus, if you’re working with an untracked entity or one that has unsaved changes, you might run into errors that aren’t immediately obvious. To keep things straightforward and avoid surprises, it’s usually better to filter by specific properties like primary keys rather than the entire entity.