How does Teams create the edit history for an uploaded document

Hello,

I would really appreciate some help in understanding how microsoft teams creates the edit history for  new version of a document which is uploaded to it.

Here is the scenario:

I download an MS Word document from teams to my laptop and over the period of a few days, I edit that document. The word document did not have track changes switched on whilst editing and therefore does not contain any edit history. 

I then upload the edited document to Teams. Despite the word document having no edit history embedded in it, in the version history of the document in Teams it shows each of the edits I have made since I downloaded it with a date and timestamp of the date on which I uploaded it, rather than the date(s) on which I actually made each of the changes to the document.

This suggests to me that the way in which Teams creates the edit history for the document is to run a compare of the newly uploaded document with the previous version stored on Teams and attribute all the changes to me on the date upon which I uploaded it.

Is this correct? If not I would appreciate a description of how that document edit history is created by Teams. If there is an official Microsoft document which describes how this works then a link to that document would be great.

Many Thanks for your help

Bigbigblue