Why is Immortal so much tinier?

Recently hit Immortal again and wondering why it's so tiny. Lack of players playing? Did Riot change matchmaking? Most of my high Immortal - Radiant friends are still hitting around the same RR. Took a break and genuinely don't know what has changed. Currently #6,000 at 10 rr when that used to be Immortal 2 in like Episode 4