When a PDF is edited and saved by appending (incremental save, the default mode of many programs), nothing is erased: the changed objects are added at the end of the file, followed by a new %%EOF marker. Each %%EOF therefore marks a version of the document. The tool rebuilds the text and information of each one. Paste the address of a Lab PDF or choose a file.

or choose a file

In real life: a hex editor (search for %%EOF), pdfresurrect, qpdf, PDF digital signatures which freeze a version. To publish a document without its history, you must « save as » a new file or flatten it, not just save it.