TLDR
Bot Verification is a requirement for bots that intend to join more than 100 servers.
Details
Bot Verification is a requirement for bots that intend to grow to a large scale. Without verification, a bot can be added to no more than 100 servers at a time. Bots become eligible to apply for verification when they join more than 75 servers.
Upon being verified, bots lose access to Privileged Intents by default. If your bot uses any Privileged Intents, you can request access to them when you apply for verification, or at any time after.
Verified bots also display a verified check mark in the Discord client.