Geographers use the term Oceania for a region that includes the continent of Australia together with most of the Pacific island countries and territories, and the seven-continent model's own seventh slot is written by some sources as "Australia/Oceania", treating the two labels as interchangeable. Continents themselves are identified by convention rather than by any strict criterion, so whether the seventh continent is the single-nation Australian landmass or the wider multi-nation Oceania region is a live difference in convention, not a factual dispute with a settled answer.
What would resolve this A single, universally adopted convention for what counts as a continent, which does not currently exist; different countries' school curricula and different atlases already choose differently (a six-continent "Australia/Oceania" model is taught in parts of Europe, a seven-continent model naming Australia alone elsewhere).
OpenContinent (Wikipedia)