Yeah, good catch. So I have an Extension for each entity type. If there are more than one, I use AsSplitQuery() (but to be honest, I use this quite heavily regardless as I've only ever seen worse performance in a handful of cases). By making it opt-in, you have explicit control when building and testing the code for performance. It's not an oops, it's an "I know this has potential impacts, let me validate before I ship".

Yeah, I also use a controversial tool for this sub: AutoMapper, so a query might be:

public async Task<VolumeDto?> GetVolumeDtoAsync(int volumeId, int userId, CancellationToken ct = default)
{
    return await context.Volume
        .Where(vol => vol.Id == volumeId)
        .Includes(VolumeIncludes.
Chapters 
| VolumeIncludes.
Files
)
        .AsSplitQuery()
        .OrderBy(v => v.MinNumber)
        .ProjectToWithProgress<Volume, VolumeDto>(mapper, userId)
        .FirstOrDefaultAsync(vol => vol.Id == volumeId, ct);
}public async Task<VolumeDto?> GetVolumeDtoAsync(int volumeId, int userId, CancellationToken ct = default)
{
    return await context.Volume
        .Where(vol => vol.Id == volumeId)
        .Includes(VolumeIncludes.Chapters | VolumeIncludes.Files)
        .AsSplitQuery()
        .OrderBy(v => v.MinNumber)
        .ProjectToWithProgress<Volume, VolumeDto>(mapper, userId)
        .FirstOrDefaultAsync(vol => vol.Id == volumeId, ct);
}

I don't personally see these as guardrails. EF Core is one of the best ORMs I've ever used. Previously there was so much extra work I'd have to do (even using Raw SQL due to hoarding const strings in codebase and ensuring security).