LibreOffice said Microsoft’s DOCX, XLSX and PPTX formats create “silent lock-in” by making documents work best inside the Office ecosystem and degrade in third-party apps.
Italo Vignoli argued those formats include undocumented features and private extensions, so files can lose layout fidelity or behave unpredictably when opened outside Microsoft software.
LibreOffice said the problem extends to preservation: a document saved today may not remain fully readable in 20 years if Microsoft drops legacy support or changes format behavior.
The project urged users and institutions to switch to open standards such as ODF for editable files and PDF/A for long-term archiving, framing that move as a step toward digital sovereignty.