I posted the draft instructions here in Tax Talk:

https://proconnect.intuit.com/community/tax-talk/discussion/form-8915-e-will-now-be-8915-f/01/186194...

"This form replaces -E for TAX YEARS beginning after 2020."

In other words, the Filing Year of 2021 is when you use -F, for covid and other disasters in 2020. For filing tax year 2020, you still use -E.