I tend to clutter my window with tabs of news articles and other resources until I have time to organize them. I recently had around two dozen, going back over two months since I found them, so I organized about half of them, and said I’d get to the others soon. Today I sit down, and all those older tabs are gone. About 7 or 8 pages that were loaded more recently are still open in the window; just the old ones are gone. They are not in the “recently closed” section of the history.
Mac 10.13.6, Version 1.26.74 Chromium: 91.0.4472.124 (Official Build) (x86_64)