Quote from Paccosi on May 20, 2022, 2:55 am

There are a couple of reasons your withdrawal can be denied, some of them are:

• Withdrawing to an INVALID address.
• System detected VPN on your account.
• You were using Termux scripts or Auto claiming softwares to earn.
• System was unable to read and verify your IP address.
• You used a SHIBA address instead of Coinbase email.
• System detected multiple accounts under your IP address.
• System detected Ad-blocking softwares on your account.

It can be one of the reasons mentioned above or any that are also listed under the restrictions section.