Caesars email support solved it for me:

Hello Todd,

Thank you for contacting Caesars Entertainment!

We appreciate your interest in your account. During Tier renewal there are times where the system is delayed in updating accounts. To better assist, I have upgraded your account to the proper Tier. We apologize for any inconvenience this delay may have caused. If we can be of further assistance, please let us know.

Thank you for being a valued Diamond member!

Have an amazing day!

Brienne
Caesars Rewards Customer Service
Caesars Entertainment
877-716-4500

Pretty ridiculous that this didn't automatically resolve by February 4. It's been 3 full days.

I gave them leeway on Feb 1 because it was the first day of the "new" Caesars year, but for this to persist for awhile is a joke.

My assumption is that this only affected Caesars accounts which earned a higher status by tiers in 2025 than had been achieved through tiers in 2024.