Okay so the answer is in:

Q4. I'm married and live in a community property state. Am I eligible for the exclusion? (updated July 7, 2021)

if you file a Married Filing Jointly return, when completing the Unemployment Compensation Exclusion Worksheet – Schedule 1, Line 8, you should report half of your unemployment compensation and half of your spouse's unemployment compensation on line 8 of the worksheet and your spouse reports the other half of your unemployment compensation and half of his or her unemployment compensation on line 9 of the worksheet.  Do not enter more than $10,200 on either line 8 or line 9 of the worksheet.  If your joint modified AGI is less than $150,000, you and your spouse can exclude up to $10,200 each. Do not exclude more than the amount of unemployment compensation you report on your Schedule 1, Line 7.

Q4. Do I need to file an amended return if I live in a community property state and did not enter the correct exclusion amount on Schedule 1, line 8? (added July 7, 2021)

A4. If you entered an exclusion amount less than what it should have been based on  FAQ So if you live in a Community Property State, you do not need to file an amended return. The IRS will recalculate your exclusion amount following this guidance and adjust your return for the difference. These corrections are currently planned for later this summer. You will receive a notice regarding the correction within 30 days of your account being adjusted.