This is a bit of an odd bug. I have the following entity, and the following tables (some stuff omitted)

CREATE TABLE [dbo].[MyEntity]
(
-- Some other columns as well, but the text column is the one that breaks
    [ExtendedAttributes] [text] COLLATE SQL_Latin1_General_CP1_CI_AS        NULL,                                           
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

When I try to insert something where the "ExtendedAttributes" text is longer than 16 characters, it's always truncated to 16 characters.

Reproducible example

// Entity, some stuff omitted
public class MyEntity
{
    public string ExtendedAttributes { get; set; };
    public int ID { get; set; }
}

// Test case
var entity = new MyEntity(id: 5, extendedAttributes: "123456789-123456789")
await using var connection = new SqlConnection("someConnectionString");
await connection.EnsureOpenAsync();
await connection.InsertAsync(entity);
var retrieved = await connection.QueryAllAsync<MyEntity>();
retrieved.First().Should().BeEquivalentTo(entity);

This results in the following error:

Expected member ExtendedAttributes to be 
"123456789-123456789" with a length of 19, but 
"123456789-123456" has a length of 16, differs near "6" (index 15).

I have checked that the value is also truncated in the database, so the issue is on the insertion part not the retrieval.
I have also done the following other steps to get more info:

• I have changed the text column to a varchar(255) - this makes it work
• I have put in a Trace. The arguments in the trace are the "correct" ones
• I have tried inserting it manually via the SqlConnection (without RepoDb) and it inserts it properly. I assume this means it's not a bug in the SQL Driver.

Potential reason

When debugging, I noticed that in InsertAsyncInternalBase, that the InsertExecutionContext.InputFields.ExtendedAttributes has the size set to 16, which is also what the string is truncated to. I don't know enough about the RepoDb codebase to understand if this is the real issue, but it seems like a promising start.