Allow unlimited length in document library

I have a document library that includes a multi line column where I track and date historical changes to the document.  I had assumed this would operate just like a multi line column in a sharepoint list, however, I seem to be running into errors when I exceed some limit of characters.  In looking at the column details, there is a setting to "Allow unlimited length in document libraries"; however, when I select this option I get the following warning:

I'm not exactly sure what this means.  In my application, the documents are uploaded, but often edited and saved.  The purpose of the multi-line column is to track the dates, names, etc. of what is happening during these changes.  I'm not exactly sure what "loss of data" means, but it sounds like I cannot edit/save existing documents within the document library AND maintain a multi-line text field.   

No one accesses the document library directly.  All uploads, changes to the document library column information, edits to the documents, saving the document, etc. is managed through a PowerApp.  I'm not sure this matters, but I'm trying to figure out how to maintain a historical record of what changes are being made.  

Any thoughts or inputs would be greatly appreciated!