What is the size limit of a cosmosdb item?

So this is one of those things that always annoys me about documentation.
Sure it's 2MB, but by who's measuring stick.

TLDR: Between 2,090,014 and 2,100,014 when Encoding.UTF8.GetByteCount(doc) or Encoding.ASCII.GetByteCount(doc)

To get there I set up the following code:

 for (int i = 10; i < 10000; i++)
        {
            var docItem = new TestItem(new string('A', i * 10000));
            string doc = JsonConvert.SerializeObject(docItem);
            log.LogInformation(" ");
            log.LogInformation(" -------------------------------------------------------------------------------------------------------------------------------------");
            log.LogInformation($" -------------------------------------------------        Doc Size = {i*10000 }       --------------------------------------------------");
            log.LogInformation(" -------------------------------------------------------------------------------------------------------------------------------------");
            
            log.LogWarning($"UTF7 - {Encoding.UTF7.GetByteCount(doc)}");
            log.LogWarning($"UTF8 - {Encoding.UTF8.GetByteCount(doc)}");
            log.LogWarning($"UTF32 - {Encoding.UTF32.GetByteCount(doc)}");
            log.LogWarning($"Unicode - {Encoding.Unicode.GetByteCount(doc)}");
            log.LogWarning($"Ascii - {Encoding.ASCII.GetByteCount(doc)}");
            log.LogInformation(" -------------------------------------------------------------------------------------------------------------------------------------");
            log.LogWarning($"UTF7 - {ASCIIEncoding.UTF7.GetByteCount(doc)}");
            log.LogWarning($"UTF8 - {ASCIIEncoding.UTF8.GetByteCount(doc)}");
            log.LogWarning($"UTF32 - {ASCIIEncoding.UTF32.GetByteCount(doc)}");
            log.LogWarning($"Unicode - {ASCIIEncoding.Unicode.GetByteCount(doc)}");
            log.LogWarning($"Ascii - {ASCIIEncoding.ASCII.GetByteCount(doc)}");
            try
            {
                await cosmosStore.CreateDocumentAsync(docItem);
            }
            catch (Exception e)
            {
                log.LogWarning(e.Message + "Caught");
            }
        }

And here's where it broke:

Update: increasing the max size to 16 MB is now possible. https://devblogs.microsoft.com/cosmosdb/larger-document-sizes-unique-index-improvements-expr-support-in-azure-cosmos-db-api-for-mongodb/