Why does Coinbase keep denying my purchase?

I've been trying to make a purchase on Coinbase, but my transaction keeps getting denied. I've checked my bank account and everything seems to be in order. Can you help me understand why Coinbase might be denying my purchase? Is it possible that there's an issue with my account or my payment method? I've tried different credit cards and even tried linking a new bank account, but I'm still having the same problem. Could it be a security measure on Coinbase's side, or is there something else I should be looking into? I'd really appreciate any insight you can provide.