OP here to close the loop on this. I called IRS and they acknowledged the error on their part. They said they have made corrections at their end but they wouldn't be sending out a new updated CP25 form. I received the $450 check last week so this case can be closed now.
But here's a shocker!! My mother, when she filed her 2019 taxes, was in a similar situation, and she also received a CP25 two weeks ago! Her story is exactly identical to mine - she also paid $450 when she requested an extension on her taxes but the CP25 is showing that amount on 1040 line 20 as $0. So the tax amount due is shown as $0. And based on the CPA's filing, she should be getting the $450 as a tax refund. She procrastinated on calling IRS but she got the $450 check today. Does she still need to call IRS and get the correction made?
