No, your loyalty level doesn’t reset all the way back to Bronze. However, if you don’t collect enough Reward Points to maintain your current status, you’ll drop down one level.
Imagine you’ve made it to the Diamond loyalty level in Month 1, which means you’ve surpassed the 20,000 Reward Points milestone. In Month 2, you’re still a Diamond player.
However, if you fail to reach 20,000 RPs by the end of Month 2, you’ll get demoted to the Platinum loyalty level in Month 3. The same rule applies to all levels.