Can immage description be suppressed for pptx files?

[Dynteq]

I just found and installed markitdown, and it works very well.
Even more than I expected. I used the command-line to convert a .pptx so I could to have a discussion with my favorite llm about it. To my surprise it also described the pictures in there which is not mentioned on the first page anywhere.
This was thankfully not a sensitive document but for others I would hate to find out after the fact that they (or the images) were send over the internet to some unnamed AI to be analyzed.

What I did after installation:
markitdown example.pptx -o example.md

Result:
an excellent .md of all the text in the document, including a description of the enclosed image

Question 1:
Can the (online) transcription of images be suppressed? (I didn't find an argument to do so)

Question2:
Does marktidown access the internet for other things? In that case it should be clearly stated as this would make it unsafe for sensitive data that should stay local.

Kind regards,
Martijn