Why are my Apex Legends lobbies so good? [duplicate]

Nothing has happened in the game itself; this is the inevitable outcome of a level system that never go down, once the game has had some time beyond its initial explosive growth. If the game had a real player ranking system, it would continue to show you the random distribution of players' skills.

When the game was growing explosively, there were so many new players coming in at Level 1 that you were likely to see low-leveled players everywhere, even if each of those players only played occasionally. That growth is mostly over (we don't have sales figures, but they haven't announced any sales milestones in a while and the Twitch viewership is down to ~10% of peak). Many casual players have moved on to other games, or play less frequently so you won't see as many of them in your games. Most of the players who continue to play Apex will be approaching Level 100 by now.