The difference in the years that the rollover contributions are made is irrelevant to how you report this on your tax return. You'll simply report that $10,000 was rolled over.
The only real difference is that the $7,000 rollover contribution will be reported on the 2020 Form 5498 for the IRA CD receiving the $7,000 rollover and the $3,000 rollover will be reported on the 2021 From 5498 for the IRA CD receiving the $3,000 rollover. Although the IRS is generally accustomed to seeing rollovers that are not completed until the year following the year of the distribution, be prepared with supporting account statements that show the distribution and contribution dates in case the IRS asks about it.
