You are on to something... I signed up to coinbase 10 years ago, but didnt use my account in about 5 because hackers got into it. Well they didnt take everything, so I reopened my account and put some money into it and also signed up for the 29.99$ a month coinbase subscription. I really dont even understand what this is getting me because coinbase keeps lowering my fees based on how many trades I make.
But searching their fee scale they say nothing about this little bonus.
All I did was make a bunch of 10 or 100$ trades to basically paper trade but with real money. Not to make money but to learn for when I put real money into it.
That's the reason you subscribe to Coinbase one with monthly subscription and got 25% rebates and 4.5% APY for holding USDC.
The link I provided is one of the benefits of Coinbase one subscription and here's what they said:
Join Coinbase One Premium and experience Coinbase without limits: zero trading fees with no caps, 25% back on all Coinbase Advanced spot fees, access to concierge support, boosted USDC and staking rewards on your full balance, higher account protection coverage, and more. Benefits vary by region.
So I guess the USDC rebates is due to your subscription.
There's no problem receiving USDC as rebates you can later trade it to USD inyo 1:1.
Why not chat the live CS to get more idea how you got rebates?