Is it too late to claim an energy credit for a new roof from 2020?

In general, roofing materials did not qualify for an energy credit in 2020. See this IRS Q & A for energy credits: https://www.irs.gov/newsroom/energy-incentives-for-individuals-residential-property-updated-questions-and-answers

No, it’s not too late if you actually qualify for the credit, but you’ll need to amend your tax year 2020 return to claim the credit, if that’s when it was installed.

As Champ Texas Roger notes above, roof expenses generally aren’t eligible for the credit, unless the roof is considered a qualified energy efficiency improvement, qualified solar electric property, or a qualified solar water heating property. 

According to Qualified energy efficiency improvements in the IRS's 2020 Instructions for Form 5695, which can be found at Prior Year Forms and Instructions, a Nonbusiness Energy Property Credit can be taken for

Any metal roof with appropriate pigmented coatings or asphalt roof with appropriate cooling granules that are specifically and primarily designed to reduce the heat gain of your home.

And, per Qualified solar electric property costs in the same instructions,

Qualified solar electric property costs are costs for property that uses solar energy to generate electricity for use in your home located in the United States. No costs relating to a solar panel or other property installed as a roof (or portion thereof) will fail to qualify solely because the property constitutes a structural component of the structure on which it is installed. Some solar roofing tiles and solar roofing shingles serve the function of both traditional roofing and solar electric collectors, and thus serve functions of both solar electric generation and structural support. These solar roofing tiles and solar roofing shingles can qualify for the credit. This is in contrast to structural components such as a roof's decking or rafters that serve only a roofing or structural function and thus do not qualify for the credit. The home doesn't have to be your main home.

If you actually do qualify for the credit, please see the TurboTax Help article How to amend (change or correct) a return you already filed for instruction on how to amend your previously-filed tax return.