A program that grants points for using Bing search, which users can redeem for gift cards, sweepstakes entries, or charitable donations.
I understand that your Microsoft Rewards dashboard shows 21,000 points, but when you check your statement or click Redeem, your available balance is only 135 points.
Please check your Microsoft Rewards points history at https://rewards.bing.com/ and review your recent transactions to verify your current points balance.
Also, check whether the 21,000 points appear as your available balance or whether they are simply displayed on your dashboard. Since the Redeem page recognizes only 135 points, that may be the current redeemable balance, but Microsoft Rewards Support would need to verify the discrepancy.
If your points history does not explain the difference, contacting Microsoft Rewards Support would be the best next step: https://rewards.bing.com/support
The support team for Bing Rewards has the essential tools and resources to investigate this issue. Please note that their response time is usually within 24 hours, but it may take longer depending on the volume of tickets they receive (first come, first served). Thank you.