A Corp was owned 100% by B Corp. A Corp paid a $3 million distribution on 12/31/2020 to B Corp.

2020 earnings and profits was $1 million.

B Corps basis in A Corp's stock was $100,000 (pursuant to sec 351, it transferred assets with a $100,000 basis to A Corp in exchange for stock when it was formed).

A Corp has shown a loss since inception 3 years ago so 2020 was a good year, 2019 and 2018 both show no taxable income as the 2017 excess loss was carried forward to 2018 and 2019. On 1/1/2020 Accumulated E&P was just less than $0.

How shall this 3 million distribution to B Corp be treated in B Corps tax return? Dividend or something else?