I’ve had groups of ‘old’ posts pop up. 3Y, 2Y 10months. That is 3 or 4 posts all quite old, surround by newer posts. Keep scrolling, another group of old posts. All the comments are less than a day old. Also sorting all by hot. Both Voyager (neé wefwef) and Memmy (for Lemmy).
Not weird communities either, ones like Reddit - the one you posted- and also Zelda, antiwork, metal…