Well, it depends on which IRS you believe. The “government by FAQ” IRS calls a “tax return for fiscal year 2019,” one that was originally due on October 15, 2018. Fiscal years are named according to the year they end, not by the edition of the form that may be used.

Q. I am a fiscal year filer who filed an extension to file my Federal income tax return for fiscal year 2019. The extended due date is April 15, 2020. Am I an “Affected Taxpayer” eligible for relief under Notice 2020-23?

A. Yes. The relief provided in Notice 2020-23 applies to Federal income tax returns and payments and postpones until July 15, 2020, all income tax return filings and payments due on or after April 1, 2020, and before July 15, 2020.

https://www.irs.gov/newsroom/filing-and-payment-deadlines-questions-and-answers