I have image data being stored in a SQL table with a field type of varbinary(max) I also store the image content type.
Using Microsoft ASP.NET Core MVC an
As @fileExtensions.GetFile(content.FileID) actually returns an FileStreamResult it wouldn't be able to render it inside html and probably just returns FileStreamResult.ToString().
Check rendered html!
Instead what you would do is a function that renders an url that triggers an action on an controller which returns the FileStreamResult.
Another alternative is to embed the image if that is what you want.
Then you have to encode your image like in this post: Convert image path to base64 string but use your memory stream instead of reading from filepath.