I got a few USDC when it was introduced on the platform, just to see how that token thing gonna work. Recently I noticed that APY reward kinda off on the last tx so contacted coinbase:
Hello,
Thank you for contacting Coinbase Support.
The APY rate is set by Coinbase and can change at anytime and you will be notified. Unless otherwise stated, any updates made will not be effective until the first day of the calendar month.
coinbase website making it even more confusing since july and aug rewards' % is off:
As of June 3rd, 2020, the APY for USDC Rewards is 0.15%.
https://help.coinbase.com/en/coinbase/taxes-reports-and-financial-services/financial-services/usd-coin-rewards-faq