Maybe a black large table cloth with sparkly confetti on it. Large 2020 date stenciled at top.
Here you go:
Black plastic tablecloth, spray adhesive on then sprinkle all over with gold or silver glitter, once hung add number balloons in silver or gold with double stick tape, add a few helium balloons in gold or silver floating next to year balloons. My dollar store all of these items.
This backdrop is adorable!