Actually it was made clear and people were saying an additional $1,400.

Here is one example:

This is from December 30, just over two weeks ago.
https://www.washingtonpost.com/business/2020/12/30/stimulus-checks-2000-dollars/

"But runoff races for Georgia’s two Senate seats — one has been clinched by Democrat Raphael Warnock and Democrat Jon Ossoff holds a lead over Republican David Perdue for the other — are once again rallying congressional Democrats and President-elect Joe Biden around the idea of an additional $1,400 in direct relief, on top of the $600 checks that were included in last month’s stimulus package."

The House bill that had been voted on was to increase the amount to $2,000.
McConnell wouldn't let the Senate vote on that bill.

Biden made the argument that if Warnock and Ossof were elected, then the Senate would vote on that bill and pass it.