Could the use of Draftsmith lead to unintentional plagiarism, due to the possible “uniformity” of text outputs from LLMs?

Draftsmith makes suggestions based on the text that you give it.

That could be your writing or it could be writing that has been prepared by a generative AI tool such as ChatGPT.

In either case, it provides suggestions on a sentence-by-sentence basis.

That means that its suggestions are highly personal and unlikely to lead to unintentional plagiarism.