Tier 1 links are your direct authority boosters while Tier 2 links help them...

https://www.cast-bookmarks.win/tiered-link-building-scales-authority-by-securing-quality-tier-1-links-and

Tier 1 links are your direct authority boosters while Tier 2 links help them stay relevant. Using Ahrefs to monitor your backlink profile helps you see how these layers push rankings up without overdoing it