At the start of Series 3 everyone will be soft reset on their ranked position by 1.5 Tiers down. That means if you ended Season 3 in Gold II, you'll be reset to Silver IV. Players in Platinum IV will be reset to Silver II, and Apex Predators will be reset to Platinum II. This reset will now occur at each split as well.

Why did my apex rank reset?

Each Ranked Season in Apex Legends is divided into two splits, which will each be played on a different map. Midway through the Season when the maps swap over for the new split, players' ranks will be soft reset to encourage them to keep grinding to reach the top ranks once again.

Do ranks reset apex?

Apex Legends Rank Reset

At the start of a new season, and when the ranked split changes mid-season, everyone's rank is reset by one and a half tiers. So if you ended the first split in Platinum II, you would start the new split in Gold IV.