Adding 2020 to your search the way you did indicates you’re looking for the keyword 2020; I’m pretty sure you were not using the after: syntax in the 2nd example. Do a search for after:2020 credit cards, which uses the syntax, and after: 2020 credit cards, which does not because of the space.

I’m not sure that you’re limiting by date there in the second search example. There appears to be a space between the after and the 2020, which would disrupt the use of syntax. Also, after 2020 would be 2021, for which Google has no results, as I can see by the experimental search after:2020 credit card late fee caps…